From 5c98d5ece86ef60999c661e57be5bfbd616fb4ea Mon Sep 17 00:00:00 2001
From: lsdsjy <1356263+lsdsjy@users.noreply.github.com>
Date: Wed, 19 Aug 2026 16:32:02 +0800
Subject: [PATCH] fix(fs): tolerate null editor placeholders

---
 ...rsistent-bash-str-replace-editor.i18n.yaml |   4 +-
 ...7-29-persistent-bash-str-replace-editor.md |   6 +-
 ...9-persistent-bash-str-replace-editor.zh.md |   6 +-
 docs/config-catalog.i18n.yaml                 |   4 +-
 docs/config-catalog.md                        |   2 +-
 docs/config-catalog.zh.md                     |   2 +-
 docs/tool-catalog.i18n.yaml                   |   4 +-
 docs/tool-catalog.md                          |  62 ++++-
 docs/tool-catalog.zh.md                       |  62 ++++-
 .../tool-str-replace-editor/README.i18n.yaml  |   4 +-
 packages/fs/tool-str-replace-editor/README.md |   2 +-
 .../fs/tool-str-replace-editor/README.zh.md   |   2 +-
 .../fs/tool-str-replace-editor/src/index.ts   |  52 ++--
 .../tests/tools.spec.ts                       |  66 ++++-
 .../minimal/model-visible.json                | 252 ++++++++++++++----
 .../minimal/win-x64/model-visible.json        | 252 ++++++++++++++----
 .../sdk/bash-tool/tool-schemas.expected.json  |  63 ++++-
 .../notifications.expected.jsonl              |  24 +-
 snapshots/sdk/persistent-tools/session.jsonl  |  24 +-
 .../tool-schemas.expected.json                |  63 ++++-
 .../tool-schemas.1.expected.json              |  63 ++++-
 .../tool-schemas.1.expected.json              |  63 ++++-
 .../tool-schemas.1.expected.json              |  63 ++++-
 .../tool-schemas.1.expected.json              |  63 ++++-
 .../sdk/text-turn/tool-schemas.expected.json  |  63 ++++-
 .../tool-schemas.expected.json                | 126 +++++++--
 .../both-mode-turn/system-prompt.expected.md  |  22 +-
 .../both-mode-turn/tool-schemas.expected.json |  63 ++++-
 .../system-prompt.expected.md                 |  22 +-
 .../code-mode-turn/system-prompt.expected.md  |  22 +-
 .../tool-schemas.expected.json                | 126 +++++++--
 .../system-prompt.expected.md                 |  22 +-
 .../tool-schemas.expected.json                |  63 ++++-
 .../tool-schemas.expected.json                |  63 ++++-
 .../lsp-definition/tool-schemas.expected.json |  63 ++++-
 .../tool-schemas.expected.json                |  63 ++++-
 .../tool-schemas.expected.json                |  63 ++++-
 .../tool-schemas.expected.json                |  63 ++++-
 .../tool-schemas.expected.json                |  63 ++++-
 .../ralph-loop/tool-schemas.1.expected.json   |  63 ++++-
 .../ralph-loop/tool-schemas.2.expected.json   |  63 ++++-
 .../tool-schemas.expected.json                |  63 ++++-
 .../tool-schemas.expected.json                |  63 ++++-
 .../tool-schemas.expected.json                |  63 ++++-
 .../text-turn/tool-schemas.expected.json      |  63 ++++-
 .../web-fetch/tool-schemas.expected.json      |  63 ++++-
 .../minimal-preset/tool-schemas.expected.json |  63 ++++-
 47 files changed, 1994 insertions(+), 625 deletions(-)

diff --git a/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.i18n.yaml b/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.i18n.yaml
index df7b3d700b..6d0a022eb0 100644
--- a/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.i18n.yaml
+++ b/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.i18n.yaml
@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.md
-2026-07-29-persistent-bash-str-replace-editor.md: e8e37b7e534773429a9c6fe0f63bb8d5460de364
-2026-07-29-persistent-bash-str-replace-editor.zh.md: 71034ba615e09e09ec03212b6d5535959df73f4a
+2026-07-29-persistent-bash-str-replace-editor.md: 1cab6e1b37a642dcbb07c4006a8c7851a8cf592c
+2026-07-29-persistent-bash-str-replace-editor.zh.md: 0edaa0c4d594a94d2860c552504d12f3cc7fdc63
diff --git a/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.md b/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.md
index e8e37b7e53..1cab6e1b37 100644
--- a/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.md
+++ b/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.md
@@ -12,7 +12,7 @@ Some deployments need a one-call Bash schema whose shell state survives across m
 
 `@deepseek-ai/dsh-tool-bash-persistent` consumes `ctx.terminals` and registers one `bash(command)` tool. It lazily creates one interactive shell per exact Agent and serializes that owner's calls. Cwd, exported variables, activated environments, functions, and background jobs persist. Random private markers delimit command output. Retained scrollback is paged backward to recover the command's original prefix; a dropped prefix is reported explicitly. A nonzero wrapped command appends `[exit code: N]`; a shell that dies before reporting that status instead appends `[shell exited: code N]`, `[shell killed by signal: SIG]`, or `[shell exited]` when the backend supplies neither. `maxOutputChars` bounds retained command output, while fixed diagnostics can extend the returned string. Timeout or cancellation closes the shell before another call can reuse uncertain state, and model-visible timeout/exit results disclose that reset. Cancellation always resets and discards the result, even when a complete status marker is already observable, so state changes the model never saw cannot survive. The configurable description defaults to persistence facts only, so network and package-mirror claims remain deployment-owned.
 
-`@deepseek-ai/dsh-tool-str-replace-editor` independently consumes `ctx.fs` and registers `str_replace_editor` with `view`, `create`, `str_replace`, and `insert`. It provides numbered text views, filtered two-level directory listings, unique literal replacement, canonical insertion boundaries, and bounded output. Paths are absolute; file views preserve content tabs so copied text remains valid literal replacement input; mutations preserve tabs outside the requested edit; and the public schema and failures use only `old_str`. The plugin can compose with persistent Bash, one-shot Bash, sandboxed Bash, or no shell.
+`@deepseek-ai/dsh-tool-str-replace-editor` independently consumes `ctx.fs` and registers `str_replace_editor` with `view`, `create`, `str_replace`, and `insert`. It provides numbered text views, filtered two-level directory listings, unique literal replacement, canonical insertion boundaries, and bounded output. Paths are absolute; file views preserve content tabs so copied text remains valid literal replacement input; mutations preserve tabs outside the requested edit; and the public schema and failures use only `old_str`. Command-specific fields accept `null` placeholders: execution treats them as omitted when the selected command does not use them, preserves required-field checks, treats `view_range: null` as a full view, and rejects `str_replace.new_str: null` so only omission requests deletion. The plugin can compose with persistent Bash, one-shot Bash, sandboxed Bash, or no shell.
 
 `dsh-system-prompt` accepts `includeHarnessIdentity: false`, while `dsh-agent-spine-demo` forwards that setting and accepts `toolBash: false`. A deployment can therefore own an exact persona and replace the spine's native Bash without duplicate prompt or tool registrations. Existing defaults remain unchanged.
 
@@ -30,6 +30,8 @@ The shipped [`minimal` agent preset](../../../../packages/preset/agent-presets/p
 
 **Modify native read/write/edit.** Rejected because it would distort their general-purpose contracts instead of adding an independently composable editor.
 
+**Reject every present `null` command field.** Rejected because model-generated calls may serialize placeholders for optional fields that the selected command does not use. The selected command still rejects `null` for required fields and for the deletion-sensitive `str_replace.new_str` field.
+
 ## Consequences
 
-Profiles can reproduce an external agent by configuring persona and descriptions while the underlying packages remain general. Persistent Bash requires an owning Agent and real PTY backend. Shell exit, timeout, or cancellation loses state. The editor delegates security and mutation policy to the mounted filesystem stack. A minimal Web agent retains Web permissions but must close its persistent shell before changing modes. Runtime-wheel consumers still need no Node installation; Linux wheels contain one executable, while macOS wheels also contain its private native helper.
+Profiles can reproduce an external agent by configuring persona and descriptions while the underlying packages remain general. Persistent Bash requires an owning Agent and real PTY backend. Shell exit, timeout, or cancellation loses state. The editor delegates security and mutation policy to the mounted filesystem stack. Nullable branches increase the command-specific fields' schema cost so unused placeholders do not force retries; execution keeps the selected command's required and deletion semantics explicit. A minimal Web agent retains Web permissions but must close its persistent shell before changing modes. Runtime-wheel consumers still need no Node installation; Linux wheels contain one executable, while macOS wheels also contain its private native helper.
diff --git a/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.zh.md b/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.zh.md
index 71034ba615..0edaa0c4d5 100644
--- a/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.zh.md
+++ b/.agents/notes/implemented/feature/2026-07-29-persistent-bash-str-replace-editor.zh.md
@@ -12,7 +12,7 @@ Status: implemented
 
 `@deepseek-ai/dsh-tool-bash-persistent` 消费 `ctx.terminals` 并注册一个 `bash(command)` 工具。它为每个精确 Agent 惰性创建一个交互式 shell，并串行化该所有者的调用。Cwd、导出的变量、已激活环境、函数和后台任务会保留。随机私有标记划分命令输出；保留的 scrollback 会向前分页，以恢复命令真正的输出前缀，若前缀已被丢弃则明确告知。经封装的命令以非零状态结束时，会追加 `[exit code: N]`；若 shell 在报告该状态前终止，则改为追加 `[shell exited: code N]`、`[shell killed by signal: SIG]`，或在后端既未提供退出码也未提供信号时追加 `[shell exited]`。`maxOutputChars` 限制保留的命令输出，而固定诊断可能使返回字符串更长。超时或取消会先关闭 shell，避免下一次调用复用状态不确定的会话，模型可见的超时／退出结果也会说明该重置。取消始终会重置 shell 并丢弃结果，即使已经能观察到完整状态标记也是如此，从而不会让模型未曾看到的状态变更得以保留。可配置描述默认只声明持久性事实，因此网络和软件包镜像等声明仍归部署所有。
 
-`@deepseek-ai/dsh-tool-str-replace-editor` 独立消费 `ctx.fs`，注册包含 `view`、`create`、`str_replace` 与 `insert` 的 `str_replace_editor`。它提供带行号文本查看、过滤后的两层目录列表、唯一字面量替换、规范插入边界和有界输出。路径必须为绝对路径；文件查看会保留内容中的制表符，因此复制的文本仍可作为有效的字面量替换输入；变更会保留请求编辑范围之外的制表符；公开 schema 与错误则只使用 `old_str`。它可以与持久 Bash、一次性 Bash、沙箱 Bash 或无 shell 组合。
+`@deepseek-ai/dsh-tool-str-replace-editor` 独立消费 `ctx.fs`，注册包含 `view`、`create`、`str_replace` 与 `insert` 的 `str_replace_editor`。它提供带行号文本查看、过滤后的两层目录列表、唯一字面量替换、规范插入边界和有界输出。路径必须为绝对路径；文件查看会保留内容中的制表符，因此复制的文本仍可作为有效的字面量替换输入；变更会保留请求编辑范围之外的制表符；公开 schema 与错误则只使用 `old_str`。命令专属字段接受 `null` 占位参数：当前命令不使用该字段时，执行会将其视为未提供；必填检查保持不变；`view_range: null` 表示查看完整文件；`str_replace.new_str: null` 会被拒绝，只有省略该字段才表示删除。它可以与持久 Bash、一次性 Bash、沙箱 Bash 或无 shell 组合。
 
 `dsh-system-prompt` 接受 `includeHarnessIdentity: false`；`dsh-agent-spine-demo` 会转发该设置，并接受 `toolBash: false`。因此部署可以拥有精确 persona，并替换 spine 的原生 Bash，而不会重复注册提示词或工具。既有默认值不变。
 
@@ -30,6 +30,8 @@ Status: implemented
 
 **修改原生 read/write/edit。** 被拒绝，因为这会扭曲其通用约定，而不是增加一个可独立组合的编辑器。
 
+**拒绝每个已提供的 `null` 命令字段。** 被拒绝，因为模型生成的调用可能为当前命令不使用的可选字段序列化占位参数。当前命令仍会拒绝必填字段以及对删除操作有影响的 `str_replace.new_str` 字段为 `null`。
+
 ## 后果
 
-Profile 可以通过配置 persona 和描述复现外部 Agent，而底层包保持通用。持久 Bash 需要拥有它的 Agent 与真实 PTY 后端；shell 退出、超时或取消会丢失状态。编辑器把安全与变更策略委托给挂载的文件系统栈。minimal Web agent 保留 Web 权限，但必须先关闭持久 shell 才能更改权限模式。运行时 wheel 包的消费方仍无需安装 Node；Linux wheel 包包含一个可执行文件，macOS wheel 包还包含其私有原生 helper。
+Profile 可以通过配置 persona 和描述复现外部 Agent，而底层包保持通用。持久 Bash 需要拥有它的 Agent 与真实 PTY 后端；shell 退出、超时或取消会丢失状态。编辑器把安全与变更策略委托给挂载的文件系统栈。可为 `null` 的分支增加了命令专属字段的 schema 成本，使未使用的占位参数不会迫使模型重试；执行仍明确保留当前命令的必填与删除语义。minimal Web agent 保留 Web 权限，但必须先关闭持久 shell 才能更改权限模式。运行时 wheel 包的消费方仍无需安装 Node；Linux wheel 包包含一个可执行文件，macOS wheel 包还包含其私有原生 helper。
diff --git a/docs/config-catalog.i18n.yaml b/docs/config-catalog.i18n.yaml
index f855cc52ac..be11483515 100644
--- a/docs/config-catalog.i18n.yaml
+++ b/docs/config-catalog.i18n.yaml
@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/config-catalog.md
-config-catalog.md: 8c9166ccbe24e8ffd3d9391de05c5207a44172d5
-config-catalog.zh.md: 6e52909c174eef64e317c9a41fa82f9699171178
+config-catalog.md: cfbaec12cad461ae8230d328dce77f1ab79bca79
+config-catalog.zh.md: 43b8d2c11fcfc313818d2f5447967b2c8fedf82d
diff --git a/docs/config-catalog.md b/docs/config-catalog.md
index 8c9166ccbe..cfbaec12ca 100644
--- a/docs/config-catalog.md
+++ b/docs/config-catalog.md
@@ -2831,7 +2831,7 @@ export interface Config {
 }
 ```
 
-Source: [`packages/fs/tool-str-replace-editor/src/index.ts:497`](../packages/fs/tool-str-replace-editor/src/index.ts)
+Source: [`packages/fs/tool-str-replace-editor/src/index.ts:505`](../packages/fs/tool-str-replace-editor/src/index.ts)
 
 <a id="deepseek-aidsh-tool-subagent"></a>
 
diff --git a/docs/config-catalog.zh.md b/docs/config-catalog.zh.md
index 6e52909c17..43b8d2c11f 100644
--- a/docs/config-catalog.zh.md
+++ b/docs/config-catalog.zh.md
@@ -2833,7 +2833,7 @@ export interface Config {
 }
 ```
 
-来源：[`packages/fs/tool-str-replace-editor/src/index.ts:497`](../packages/fs/tool-str-replace-editor/src/index.ts)
+来源：[`packages/fs/tool-str-replace-editor/src/index.ts:505`](../packages/fs/tool-str-replace-editor/src/index.ts)
 
 <a id="deepseek-aidsh-tool-subagent"></a>
 
diff --git a/docs/tool-catalog.i18n.yaml b/docs/tool-catalog.i18n.yaml
index 38ad384da8..5b23decb3c 100644
--- a/docs/tool-catalog.i18n.yaml
+++ b/docs/tool-catalog.i18n.yaml
@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/tool-catalog.md
-tool-catalog.md: 0cd8560a6851f0195e2272d1bd3b0bec2c171ac4
-tool-catalog.zh.md: cb225bc11afa6a6b022f2c7c104d4e1286f89260
+tool-catalog.md: 7b166243fc3f5ef2c1bacdddaf5ee44c5b155622
+tool-catalog.zh.md: b44a0de4968dbcd760db546037f35e844608c819
diff --git a/docs/tool-catalog.md b/docs/tool-catalog.md
index 0cd8560a68..7b166243fc 100644
--- a/docs/tool-catalog.md
+++ b/docs/tool-catalog.md
@@ -566,6 +566,7 @@ Custom editing tool for viewing, creating and editing files
 * If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep
 * The `create` command cannot be used if the specified `path` already exists as a file
 * If a `command` generates a long output, it will be truncated and marked with `<response clipped>`
+* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match
 
 Notes for using the `str_replace` command:
 * The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!
@@ -591,27 +592,62 @@ Notes for using the `str_replace` command:
       "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
     },
     "file_text": {
-      "type": "string",
-      "description": "Required parameter of `create` command, with the content of the file to be created."
+      "oneOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
     },
     "insert_line": {
-      "type": "integer",
-      "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+      "oneOf": [
+        {
+          "type": "integer"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
     },
     "new_str": {
-      "type": "string",
-      "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+      "oneOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
     },
     "old_str": {
-      "type": "string",
-      "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+      "oneOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
     },
     "view_range": {
-      "type": "array",
-      "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-      "items": {
-        "type": "integer"
-      }
+      "oneOf": [
+        {
+          "type": "array",
+          "items": {
+            "type": "integer"
+          }
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
     }
   },
   "required": [
diff --git a/docs/tool-catalog.zh.md b/docs/tool-catalog.zh.md
index cb225bc11a..b44a0de496 100644
--- a/docs/tool-catalog.zh.md
+++ b/docs/tool-catalog.zh.md
@@ -571,6 +571,7 @@ pwsh 工具是 Windows 组合中 bash 执行器 seam 的 PowerShell 方言消费
 * 如果 `path` 是文件，`view` 会显示应用 `cat -n` 后的结果。如果 `path` 是目录，`view` 会列出最多向下 2 层的非隐藏文件和目录
 * 如果指定的 `create` 命令目标 `path` 已作为文件存在，则不能使用该命令
 * 如果 `command` 产生较长输出，输出会被截断并标记为 `<response clipped>`
+* 当前命令不使用某个参数时，值为 `null` 的占位参数视为未提供。必填参数仍须提供值；删除匹配内容时应省略 `str_replace.new_str`，而不是将其设为 `null`
 
 使用 `str_replace` 命令时请注意：
 
@@ -597,27 +598,62 @@ pwsh 工具是 Windows 组合中 bash 执行器 seam 的 PowerShell 方言消费
       "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
     },
     "file_text": {
-      "type": "string",
-      "description": "Required parameter of `create` command, with the content of the file to be created."
+      "oneOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
     },
     "insert_line": {
-      "type": "integer",
-      "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+      "oneOf": [
+        {
+          "type": "integer"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
     },
     "new_str": {
-      "type": "string",
-      "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+      "oneOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
     },
     "old_str": {
-      "type": "string",
-      "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+      "oneOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
     },
     "view_range": {
-      "type": "array",
-      "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-      "items": {
-        "type": "integer"
-      }
+      "oneOf": [
+        {
+          "type": "array",
+          "items": {
+            "type": "integer"
+          }
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
     }
   },
   "required": [
diff --git a/packages/fs/tool-str-replace-editor/README.i18n.yaml b/packages/fs/tool-str-replace-editor/README.i18n.yaml
index 15b807b70f..6d9a4de276 100644
--- a/packages/fs/tool-str-replace-editor/README.i18n.yaml
+++ b/packages/fs/tool-str-replace-editor/README.i18n.yaml
@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/fs/tool-str-replace-editor/README.md
-README.md: 8b4772cc4eb40e23a5d6ea8e409188b5033318ba
-README.zh.md: db2d5f2aee60b864135718007bd02bed09c77bb5
+README.md: 6d1cd99827b392e459267f02e028e87dd595e6e8
+README.zh.md: 49baaf4bfa92144e9a785266026276e4b7f0ce3e
diff --git a/packages/fs/tool-str-replace-editor/README.md b/packages/fs/tool-str-replace-editor/README.md
index 8b4772cc4e..6d1cd99827 100644
--- a/packages/fs/tool-str-replace-editor/README.md
+++ b/packages/fs/tool-str-replace-editor/README.md
@@ -13,7 +13,7 @@ Standalone model-facing `str_replace_editor` over `ctx.fs`. It can be composed w
 
 ## Tool
 
-The schema provides `view`, `create`, `str_replace`, and `insert` over absolute paths. File views use one-based line numbers and preserve content tabs, so displayed text remains valid literal replacement input; directory views omit hidden, dependency, and Python-cache entries and descend two levels. A metadata miss from `view`, `str_replace`, or `insert` records confirmed absence before returning `FS_NOT_FOUND`, so a later `create` can recover an externally deleted path through the mounted policy's guarded-create flow; absence never authorizes `str_replace` or `insert`. Replacement requires one unique literal match and reports errors only in the public `old_str` vocabulary. Insert follows the selected zero-based insertion boundary without adding an implicit trailing newline. Mutations preserve tabs outside the requested edit.
+The schema provides `view`, `create`, `str_replace`, and `insert` over absolute paths. File views use one-based line numbers and preserve content tabs, so displayed text remains valid literal replacement input; directory views omit hidden, dependency, and Python-cache entries and descend two levels. A metadata miss from `view`, `str_replace`, or `insert` records confirmed absence before returning `FS_NOT_FOUND`, so a later `create` can recover an externally deleted path through the mounted policy's guarded-create flow; absence never authorizes `str_replace` or `insert`. Replacement requires one unique literal match and reports errors only in the public `old_str` vocabulary. Command-specific fields accept `null` placeholders: execution treats them as omitted when the selected command does not use them, required fields remain required, `view_range: null` selects the full view, and `str_replace.new_str: null` is rejected so deletion requires omission. Insert follows its selected zero-based boundary without adding an implicit trailing newline. Mutations preserve tabs outside the requested edit.
 
 ## Model Experience
 
diff --git a/packages/fs/tool-str-replace-editor/README.zh.md b/packages/fs/tool-str-replace-editor/README.zh.md
index db2d5f2aee..49baaf4bfa 100644
--- a/packages/fs/tool-str-replace-editor/README.zh.md
+++ b/packages/fs/tool-str-replace-editor/README.zh.md
@@ -13,7 +13,7 @@
 
 ## 工具
 
-schema 提供针对绝对路径的 `view`、`create`、`str_replace` 与 `insert`。文件查看使用从 1 开始的行号，并保留内容中的制表符，因此显示的文本仍可作为有效的字面量替换输入；目录查看忽略隐藏、依赖与 Python 缓存条目并下探两层。`view`、`str_replace` 或 `insert` 发生元数据未命中时，工具会在返回 `FS_NOT_FOUND` 前记录确认缺失，因此后续 `create` 可以通过已挂载策略的防护创建流程恢复外部删除的路径；缺失状态绝不会授权 `str_replace` 或 `insert`。替换要求字面量唯一匹配，错误只使用公开的 `old_str` 词汇。插入遵循所选的零基插入边界，不会隐式补尾换行。修改操作会保留请求编辑范围之外的制表符。
+schema 提供针对绝对路径的 `view`、`create`、`str_replace` 与 `insert`。文件查看使用从 1 开始的行号，并保留内容中的制表符，因此显示的文本仍可作为有效的字面量替换输入；目录查看忽略隐藏、依赖与 Python 缓存条目并下探两层。`view`、`str_replace` 或 `insert` 发生元数据未命中时，工具会在返回 `FS_NOT_FOUND` 前记录确认缺失，因此后续 `create` 可以通过已挂载策略的防护创建流程恢复外部删除的路径；缺失状态绝不会授权 `str_replace` 或 `insert`。替换要求字面量唯一匹配，错误只使用公开的 `old_str` 词汇。命令专属字段接受 `null` 占位参数：当前命令不使用该字段时，执行会将其视为未提供；必填字段仍为必填；`view_range: null` 表示查看完整文件；`str_replace.new_str: null` 会被拒绝，因此删除匹配内容必须省略该字段。插入遵循所选的零基边界，不会隐式补尾换行。修改操作会保留请求编辑范围之外的制表符。
 
 ## 模型体验
 
diff --git a/packages/fs/tool-str-replace-editor/src/index.ts b/packages/fs/tool-str-replace-editor/src/index.ts
index c8afd16064..f77736685e 100644
--- a/packages/fs/tool-str-replace-editor/src/index.ts
+++ b/packages/fs/tool-str-replace-editor/src/index.ts
@@ -22,6 +22,7 @@ Custom editing tool for viewing, creating and editing files
 * If \`path\` is a file, \`view\` displays the result of applying \`cat -n\`. If \`path\` is a directory, \`view\` lists non-hidden files and directories up to 2 levels deep
 * The \`create\` command cannot be used if the specified \`path\` already exists as a file
 * If a \`command\` generates a long output, it will be truncated and marked with \`<response clipped>\`
+* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit \`str_replace.new_str\` rather than setting it to null when deleting a match
 
 Notes for using the \`str_replace\` command:
 * The \`old_str\` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!
@@ -276,9 +277,12 @@ async function replaceInFile(
   policy: MutationPolicy,
   path: string,
   oldStr: string | undefined,
-  newStr: string | undefined,
+  newStr: string | null | undefined,
   exec: ToolRunContext,
 ): Promise<string> {
+  if (newStr === null) {
+    throw new Error('Parameter `new_str` must be omitted or contain a string for command: str_replace')
+  }
   const sandboxPolicy = policy.resolve(exec)
   const target = await resolveTarget(ctx, path, exec.signal)
   const intent = await ctx.waterfall('fs/edit-intent', target, exec, () => undefined)
@@ -372,10 +376,10 @@ interface ResolvedConfig {
 function presentEditorCall(args: {
   command: 'view' | 'create' | 'str_replace' | 'insert'
   path: string
-  file_text?: string
-  insert_line?: number
-  new_str?: string
-  old_str?: string
+  file_text?: string | null
+  insert_line?: number | null
+  new_str?: string | null
+  old_str?: string | null
 }): ToolCallView {
   switch (args.command) {
     case 'view':
@@ -410,7 +414,9 @@ function presentEditorCall(args: {
         kind: 'edit',
         locations: [{
           path: args.path,
-          ...args.insert_line === undefined ? {} : { line: Math.max(1, args.insert_line + 1) },
+          ...args.insert_line === undefined || args.insert_line === null
+            ? {}
+            : { line: Math.max(1, args.insert_line + 1) },
         }],
       }
   }
@@ -435,25 +441,27 @@ function registerStrReplaceEditor(ctx: Context, config: ResolvedConfig): void {
         description: 'Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`.',
       },
       file_text: {
-        type: 'string',
-        description: 'Required parameter of `create` command, with the content of the file to be created.',
+        oneOf: [{ type: 'string' }, { type: 'null' }],
+        description: 'Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter.',
       },
       insert_line: {
-        type: 'integer',
-        description: 'Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`.',
+        oneOf: [{ type: 'integer' }, { type: 'null' }],
+        description: 'Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter.',
       },
       new_str: {
-        type: 'string',
-        description: 'Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert.',
+        oneOf: [{ type: 'string' }, { type: 'null' }],
+        description: 'Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter.',
       },
       old_str: {
-        type: 'string',
-        description: 'Required parameter of `str_replace` command containing the string in `path` to replace.',
+        oneOf: [{ type: 'string' }, { type: 'null' }],
+        description: 'Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter.',
       },
       view_range: {
-        type: 'array',
-        items: { type: 'integer' },
-        description: 'Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.',
+        oneOf: [
+          { type: 'array', items: { type: 'integer' } },
+          { type: 'null' },
+        ],
+        description: 'Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.',
       },
     },
     output: {
@@ -463,15 +471,15 @@ function registerStrReplaceEditor(ctx: Context, config: ResolvedConfig): void {
     async execute(args, exec) {
       switch (args.command) {
         case 'view':
-          return viewPath(ctx, args.path, args.view_range, config.maxOutputChars, exec)
+          return viewPath(ctx, args.path, args.view_range ?? undefined, config.maxOutputChars, exec)
         case 'create':
-          return createFile(ctx, policy, args.path, args.file_text, exec)
+          return createFile(ctx, policy, args.path, args.file_text ?? undefined, exec)
         case 'str_replace':
           return replaceInFile(
             ctx,
             policy,
             args.path,
-            args.old_str,
+            args.old_str ?? undefined,
             args.new_str,
             exec,
           )
@@ -480,8 +488,8 @@ function registerStrReplaceEditor(ctx: Context, config: ResolvedConfig): void {
             ctx,
             policy,
             args.path,
-            args.insert_line,
-            args.new_str,
+            args.insert_line ?? undefined,
+            args.new_str ?? undefined,
             exec,
           )
       }
diff --git a/packages/fs/tool-str-replace-editor/tests/tools.spec.ts b/packages/fs/tool-str-replace-editor/tests/tools.spec.ts
index e363666606..fce0c37950 100644
--- a/packages/fs/tool-str-replace-editor/tests/tools.spec.ts
+++ b/packages/fs/tool-str-replace-editor/tests/tools.spec.ts
@@ -91,14 +91,27 @@ describe('tool-str-replace-editor', () => {
     expect(ctx.tools.schemas().map(item => item.name)).toEqual(['str_replace_editor'])
     expect(schema?.description).toBe('custom editor description')
     const properties = (schema?.parameters as {
-      properties: Record<string, { type?: string; items?: { type?: string } }>
+      properties: Record<string, {
+        type?: string
+        items?: { type?: string }
+        oneOf?: { type?: string; items?: { type?: string } }[]
+      }>
     }).properties
     expect(properties).not.toHaveProperty('replace_all')
-    expect(properties.insert_line?.type).toBe('integer')
-    expect(properties.view_range?.items?.type).toBe('integer')
+    expect(properties.file_text?.oneOf?.map(option => option.type)).toEqual(['string', 'null'])
+    expect(properties.insert_line?.oneOf?.map(option => option.type)).toEqual(['integer', 'null'])
+    expect(properties.new_str?.oneOf?.map(option => option.type)).toEqual(['string', 'null'])
+    expect(properties.old_str?.oneOf?.map(option => option.type)).toEqual(['string', 'null'])
+    expect(properties.view_range?.oneOf?.map(option => option.type)).toEqual(['array', 'null'])
+    expect(properties.view_range?.oneOf?.[0]?.items?.type).toBe('integer')
     expect(ctx.tools.get('str_replace_editor')?.presentCall?.({
       command: 'view',
       path: '/workspace/a.txt',
+      file_text: null,
+      insert_line: null,
+      new_str: null,
+      old_str: null,
+      view_range: null,
     })).toMatchObject({
       card: 'generic',
       kind: 'read',
@@ -108,6 +121,10 @@ describe('tool-str-replace-editor', () => {
       command: 'create',
       path: '/workspace/a.txt',
       file_text: 'hello',
+      insert_line: null,
+      new_str: null,
+      old_str: null,
+      view_range: null,
     })).toMatchObject({
       card: 'diff',
       diffs: [{ path: '/workspace/a.txt', oldText: null, newText: 'hello' }],
@@ -117,15 +134,31 @@ describe('tool-str-replace-editor', () => {
       path: '/workspace/a.txt',
       old_str: 'old',
       new_str: 'new',
+      file_text: null,
+      insert_line: null,
+      view_range: null,
     })).toMatchObject({
       card: 'diff',
       diffs: [{ path: '/workspace/a.txt', oldText: 'old', newText: 'new' }],
     })
+    expect(ctx.tools.get('str_replace_editor')?.presentCall?.({
+      command: 'insert',
+      path: '/workspace/a.txt',
+      insert_line: null,
+      new_str: 'x',
+    })).toMatchObject({
+      card: 'generic',
+      kind: 'edit',
+      locations: [{ path: '/workspace/a.txt' }],
+    })
     expect(ctx.tools.get('str_replace_editor')?.presentCall?.({
       command: 'insert',
       path: '/workspace/a.txt',
       insert_line: 0,
       new_str: 'x',
+      file_text: null,
+      old_str: null,
+      view_range: null,
     })).toMatchObject({
       card: 'generic',
       kind: 'edit',
@@ -162,8 +195,22 @@ describe('tool-str-replace-editor', () => {
       command: 'create',
       path: sample,
       file_text: 'one\ntwo\nthree\n',
+      insert_line: null,
+      new_str: null,
+      old_str: null,
+      view_range: null,
     }))).toBe(`New file created successfully at: ${sample}`)
 
+    expect(text(await call(ctx, owner, {
+      command: 'view',
+      path: sample,
+      file_text: null,
+      insert_line: null,
+      new_str: null,
+      old_str: null,
+      view_range: null,
+    }))).toContain('     2  two')
+
     expect(text(await call(ctx, owner, {
       command: 'view',
       path: sample,
@@ -181,6 +228,9 @@ describe('tool-str-replace-editor', () => {
       path: sample,
       old_str: 'two',
       new_str: 'TWO',
+      file_text: null,
+      insert_line: null,
+      view_range: null,
     }))).toBe(`The file ${sample} has been edited successfully.`)
     expect(text(await call(ctx, owner, {
       command: 'str_replace',
@@ -192,6 +242,9 @@ describe('tool-str-replace-editor', () => {
       path: sample,
       insert_line: 1,
       new_str: 'between',
+      file_text: null,
+      old_str: null,
+      view_range: null,
     }))).toBe(`The file ${sample} has been edited successfully.`)
     expect(await readFile(sample, 'utf8')).toBe('one\nbetween\n\nthree\n')
   })
@@ -398,6 +451,8 @@ describe('tool-str-replace-editor', () => {
     await mkdir(directory)
 
     const cases = [
+      { command: null, path: ambiguous },
+      { command: 'view', path: null },
       { command: 'view', path: '' },
       { command: 'view', path: join(root, 'missing.txt') },
       { command: 'view', path: ambiguous, view_range: [1] },
@@ -407,10 +462,15 @@ describe('tool-str-replace-editor', () => {
       { command: 'view', path: threeLines, view_range: [2, 1] },
       { command: 'view', path: directory, view_range: [1, 1] },
       { command: 'create', path: join(root, 'new.txt') },
+      { command: 'create', path: join(root, 'new.txt'), file_text: null },
       { command: 'create', path: ambiguous, file_text: 'overwrite' },
       { command: 'str_replace', path: ambiguous, new_str: 'x' },
+      { command: 'str_replace', path: ambiguous, old_str: null, new_str: 'x' },
+      { command: 'str_replace', path: ambiguous, old_str: 'same same', new_str: null },
       { command: 'str_replace', path: ambiguous, old_str: '', new_str: 'x' },
       { command: 'insert', path: ambiguous, new_str: 'x' },
+      { command: 'insert', path: ambiguous, insert_line: null, new_str: 'x' },
+      { command: 'insert', path: ambiguous, insert_line: 0, new_str: null },
       { command: 'insert', path: ambiguous, insert_line: -1, new_str: 'x' },
       { command: 'insert', path: ambiguous, insert_line: 1.5, new_str: 'x' },
       { command: 'insert', path: ambiguous, insert_line: 99, new_str: 'x' },
diff --git a/scripts/snapshots/python-sdk-single-exe/minimal/model-visible.json b/scripts/snapshots/python-sdk-single-exe/minimal/model-visible.json
index 86fcecb5b1..3cbc88cb08 100644
--- a/scripts/snapshots/python-sdk-single-exe/minimal/model-visible.json
+++ b/scripts/snapshots/python-sdk-single-exe/minimal/model-visible.json
@@ -24,7 +24,7 @@
         "type": "function",
         "function": {
           "name": "str_replace_editor",
-          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
           "parameters": {
             "type": "object",
             "properties": {
@@ -43,27 +43,62 @@
                 "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
               },
               "file_text": {
-                "type": "string",
-                "description": "Required parameter of `create` command, with the content of the file to be created."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "insert_line": {
-                "type": "integer",
-                "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+                "oneOf": [
+                  {
+                    "type": "integer"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "new_str": {
-                "type": "string",
-                "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
               },
               "old_str": {
-                "type": "string",
-                "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "view_range": {
-                "type": "array",
-                "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-                "items": {
-                  "type": "integer"
-                }
+                "oneOf": [
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "integer"
+                    }
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
               }
             },
             "required": [
@@ -110,7 +145,7 @@
         "type": "function",
         "function": {
           "name": "str_replace_editor",
-          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
           "parameters": {
             "type": "object",
             "properties": {
@@ -129,27 +164,62 @@
                 "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
               },
               "file_text": {
-                "type": "string",
-                "description": "Required parameter of `create` command, with the content of the file to be created."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "insert_line": {
-                "type": "integer",
-                "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+                "oneOf": [
+                  {
+                    "type": "integer"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "new_str": {
-                "type": "string",
-                "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
               },
               "old_str": {
-                "type": "string",
-                "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "view_range": {
-                "type": "array",
-                "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-                "items": {
-                  "type": "integer"
-                }
+                "oneOf": [
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "integer"
+                    }
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
               }
             },
             "required": [
@@ -210,7 +280,7 @@
         "type": "function",
         "function": {
           "name": "str_replace_editor",
-          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
           "parameters": {
             "type": "object",
             "properties": {
@@ -229,27 +299,62 @@
                 "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
               },
               "file_text": {
-                "type": "string",
-                "description": "Required parameter of `create` command, with the content of the file to be created."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "insert_line": {
-                "type": "integer",
-                "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+                "oneOf": [
+                  {
+                    "type": "integer"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "new_str": {
-                "type": "string",
-                "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
               },
               "old_str": {
-                "type": "string",
-                "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "view_range": {
-                "type": "array",
-                "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-                "items": {
-                  "type": "integer"
-                }
+                "oneOf": [
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "integer"
+                    }
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
               }
             },
             "required": [
@@ -324,7 +429,7 @@
         "type": "function",
         "function": {
           "name": "str_replace_editor",
-          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
           "parameters": {
             "type": "object",
             "properties": {
@@ -343,27 +448,62 @@
                 "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
               },
               "file_text": {
-                "type": "string",
-                "description": "Required parameter of `create` command, with the content of the file to be created."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "insert_line": {
-                "type": "integer",
-                "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+                "oneOf": [
+                  {
+                    "type": "integer"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "new_str": {
-                "type": "string",
-                "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
               },
               "old_str": {
-                "type": "string",
-                "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "view_range": {
-                "type": "array",
-                "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-                "items": {
-                  "type": "integer"
-                }
+                "oneOf": [
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "integer"
+                    }
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
               }
             },
             "required": [
diff --git a/scripts/snapshots/python-sdk-single-exe/minimal/win-x64/model-visible.json b/scripts/snapshots/python-sdk-single-exe/minimal/win-x64/model-visible.json
index d630a7bf10..f8d606e8ea 100644
--- a/scripts/snapshots/python-sdk-single-exe/minimal/win-x64/model-visible.json
+++ b/scripts/snapshots/python-sdk-single-exe/minimal/win-x64/model-visible.json
@@ -24,7 +24,7 @@
         "type": "function",
         "function": {
           "name": "str_replace_editor",
-          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
           "parameters": {
             "type": "object",
             "properties": {
@@ -43,27 +43,62 @@
                 "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
               },
               "file_text": {
-                "type": "string",
-                "description": "Required parameter of `create` command, with the content of the file to be created."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "insert_line": {
-                "type": "integer",
-                "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+                "oneOf": [
+                  {
+                    "type": "integer"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "new_str": {
-                "type": "string",
-                "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
               },
               "old_str": {
-                "type": "string",
-                "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "view_range": {
-                "type": "array",
-                "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-                "items": {
-                  "type": "integer"
-                }
+                "oneOf": [
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "integer"
+                    }
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
               }
             },
             "required": [
@@ -110,7 +145,7 @@
         "type": "function",
         "function": {
           "name": "str_replace_editor",
-          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
           "parameters": {
             "type": "object",
             "properties": {
@@ -129,27 +164,62 @@
                 "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
               },
               "file_text": {
-                "type": "string",
-                "description": "Required parameter of `create` command, with the content of the file to be created."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "insert_line": {
-                "type": "integer",
-                "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+                "oneOf": [
+                  {
+                    "type": "integer"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "new_str": {
-                "type": "string",
-                "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
               },
               "old_str": {
-                "type": "string",
-                "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "view_range": {
-                "type": "array",
-                "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-                "items": {
-                  "type": "integer"
-                }
+                "oneOf": [
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "integer"
+                    }
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
               }
             },
             "required": [
@@ -210,7 +280,7 @@
         "type": "function",
         "function": {
           "name": "str_replace_editor",
-          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
           "parameters": {
             "type": "object",
             "properties": {
@@ -229,27 +299,62 @@
                 "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
               },
               "file_text": {
-                "type": "string",
-                "description": "Required parameter of `create` command, with the content of the file to be created."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "insert_line": {
-                "type": "integer",
-                "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+                "oneOf": [
+                  {
+                    "type": "integer"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "new_str": {
-                "type": "string",
-                "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
               },
               "old_str": {
-                "type": "string",
-                "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "view_range": {
-                "type": "array",
-                "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-                "items": {
-                  "type": "integer"
-                }
+                "oneOf": [
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "integer"
+                    }
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
               }
             },
             "required": [
@@ -324,7 +429,7 @@
         "type": "function",
         "function": {
           "name": "str_replace_editor",
-          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+          "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
           "parameters": {
             "type": "object",
             "properties": {
@@ -343,27 +448,62 @@
                 "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
               },
               "file_text": {
-                "type": "string",
-                "description": "Required parameter of `create` command, with the content of the file to be created."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "insert_line": {
-                "type": "integer",
-                "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+                "oneOf": [
+                  {
+                    "type": "integer"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "new_str": {
-                "type": "string",
-                "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
               },
               "old_str": {
-                "type": "string",
-                "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+                "oneOf": [
+                  {
+                    "type": "string"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
               },
               "view_range": {
-                "type": "array",
-                "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-                "items": {
-                  "type": "integer"
-                }
+                "oneOf": [
+                  {
+                    "type": "array",
+                    "items": {
+                      "type": "integer"
+                    }
+                  },
+                  {
+                    "type": "null"
+                  }
+                ],
+                "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
               }
             },
             "required": [
diff --git a/snapshots/sdk/bash-tool/tool-schemas.expected.json b/snapshots/sdk/bash-tool/tool-schemas.expected.json
index 7672d1155f..e8fd1b5981 100644
--- a/snapshots/sdk/bash-tool/tool-schemas.expected.json
+++ b/snapshots/sdk/bash-tool/tool-schemas.expected.json
@@ -359,7 +359,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -378,27 +378,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/sdk/persistent-tools/notifications.expected.jsonl b/snapshots/sdk/persistent-tools/notifications.expected.jsonl
index 3b8e08a361..fe4872b440 100644
--- a/snapshots/sdk/persistent-tools/notifications.expected.jsonl
+++ b/snapshots/sdk/persistent-tools/notifications.expected.jsonl
@@ -39,32 +39,32 @@
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/end","seq":37,"time":0,"data":{"turn":1,"step":3}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/start","seq":38,"time":0,"data":{"turn":1,"step":4}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":39,"time":0,"data":{"turn":1,"step":4,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":40,"time":0,"data":{"turn":1,"step":4,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-create","name":"str_replace_editor","argumentsDelta":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\"}"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":41,"time":0,"data":{"turn":1,"step":4,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\"}"}}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":40,"time":0,"data":{"turn":1,"step":4,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-create","name":"str_replace_editor","argumentsDelta":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\",\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":41,"time":0,"data":{"turn":1,"step":4,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\",\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":42,"time":0,"data":{"turn":1,"step":4,"chunk":{"type":"usage","usage":{"inputTokens":3,"outputTokens":3}}}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":43,"time":0,"data":{"turn":1,"step":4,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":44,"time":0,"data":{"turn":1,"step":4,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[39,40,41,42,43],"surfaceOp":"append"}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/call","seq":45,"time":0,"data":{"turn":1,"step":4,"callId":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\"}"}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":44,"time":0,"data":{"turn":1,"step":4,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\",\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[39,40,41,42,43],"surfaceOp":"append"}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/call","seq":45,"time":0,"data":{"turn":1,"step":4,"callId":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\",\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/result","seq":46,"time":0,"data":{"turn":1,"step":4,"message":{"source":{"kind":"tool","callId":"editor-create"},"content":[{"type":"tool-result","toolCallId":"editor-create","content":[{"type":"text","text":"New file created successfully at: {{cwd}}/note.txt"}],"isError":false}],"role":"user","id":"{{sessionId}}"}},"sourceEventSeqs":[45],"surfaceOp":"append"}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/end","seq":47,"time":0,"data":{"turn":1,"step":4}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/start","seq":48,"time":0,"data":{"turn":1,"step":5}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":49,"time":0,"data":{"turn":1,"step":5,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":50,"time":0,"data":{"turn":1,"step":5,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-view","name":"str_replace_editor","argumentsDelta":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\"}"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":51,"time":0,"data":{"turn":1,"step":5,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\"}"}}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":50,"time":0,"data":{"turn":1,"step":5,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-view","name":"str_replace_editor","argumentsDelta":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":null,\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":51,"time":0,"data":{"turn":1,"step":5,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":null,\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":52,"time":0,"data":{"turn":1,"step":5,"chunk":{"type":"usage","usage":{"inputTokens":3,"outputTokens":3}}}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":53,"time":0,"data":{"turn":1,"step":5,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":54,"time":0,"data":{"turn":1,"step":5,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[49,50,51,52,53],"surfaceOp":"append"}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/call","seq":55,"time":0,"data":{"turn":1,"step":5,"callId":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\"}"}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":54,"time":0,"data":{"turn":1,"step":5,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":null,\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[49,50,51,52,53],"surfaceOp":"append"}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/call","seq":55,"time":0,"data":{"turn":1,"step":5,"callId":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":null,\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/result","seq":56,"time":0,"data":{"turn":1,"step":5,"message":{"source":{"kind":"tool","callId":"editor-view"},"content":[{"type":"tool-result","toolCallId":"editor-view","content":[{"type":"text","text":"Here's the content of {{cwd}}/note.txt with line numbers (which has a total of 3 lines):\n     1  target:\n     2  \told\n     3  \n"}],"isError":false}],"role":"user","id":"{{sessionId}}"}},"sourceEventSeqs":[55],"surfaceOp":"append"}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/end","seq":57,"time":0,"data":{"turn":1,"step":5}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/start","seq":58,"time":0,"data":{"turn":1,"step":6}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":59,"time":0,"data":{"turn":1,"step":6,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":60,"time":0,"data":{"turn":1,"step":6,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-replace","name":"str_replace_editor","argumentsDelta":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\"}"}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":61,"time":0,"data":{"turn":1,"step":6,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\"}"}}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":60,"time":0,"data":{"turn":1,"step":6,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-replace","name":"str_replace_editor","argumentsDelta":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\",\"file_text\":null,\"insert_line\":null,\"view_range\":null}"}}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":61,"time":0,"data":{"turn":1,"step":6,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\",\"file_text\":null,\"insert_line\":null,\"view_range\":null}"}}}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":62,"time":0,"data":{"turn":1,"step":6,"chunk":{"type":"usage","usage":{"inputTokens":3,"outputTokens":3}}}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/chunk","seq":63,"time":0,"data":{"turn":1,"step":6,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":64,"time":0,"data":{"turn":1,"step":6,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[59,60,61,62,63],"surfaceOp":"append"}}}
-{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/call","seq":65,"time":0,"data":{"turn":1,"step":6,"callId":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\"}"}}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"assistant/message","seq":64,"time":0,"data":{"turn":1,"step":6,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\",\"file_text\":null,\"insert_line\":null,\"view_range\":null}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[59,60,61,62,63],"surfaceOp":"append"}}}
+{"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/call","seq":65,"time":0,"data":{"turn":1,"step":6,"callId":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\",\"file_text\":null,\"insert_line\":null,\"view_range\":null}"}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"tool/result","seq":66,"time":0,"data":{"turn":1,"step":6,"message":{"source":{"kind":"tool","callId":"editor-replace"},"content":[{"type":"tool-result","toolCallId":"editor-replace","content":[{"type":"text","text":"The file {{cwd}}/note.txt has been edited successfully."}],"isError":false}],"role":"user","id":"{{sessionId}}"}},"sourceEventSeqs":[65],"surfaceOp":"append"}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/end","seq":67,"time":0,"data":{"turn":1,"step":6}}}}
 {"method":"session.event","params":{"sessionId":"{{sessionId}}","event":{"type":"step/start","seq":68,"time":0,"data":{"turn":1,"step":7}}}}
diff --git a/snapshots/sdk/persistent-tools/session.jsonl b/snapshots/sdk/persistent-tools/session.jsonl
index 8024d37199..b382309331 100644
--- a/snapshots/sdk/persistent-tools/session.jsonl
+++ b/snapshots/sdk/persistent-tools/session.jsonl
@@ -39,32 +39,32 @@
 {"type":"step/end","data":{"turn":1,"step":3}}
 {"type":"step/start","data":{"turn":1,"step":4}}
 {"type":"assistant/chunk","data":{"turn":1,"step":4,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}
-{"type":"assistant/chunk","data":{"turn":1,"step":4,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-create","name":"str_replace_editor","argumentsDelta":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\"}"}}}
-{"type":"assistant/chunk","data":{"turn":1,"step":4,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\"}"}}}}
+{"type":"assistant/chunk","data":{"turn":1,"step":4,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-create","name":"str_replace_editor","argumentsDelta":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\",\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}
+{"type":"assistant/chunk","data":{"turn":1,"step":4,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\",\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":4,"chunk":{"type":"usage","usage":{"inputTokens":3,"outputTokens":3}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":4,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
-{"type":"assistant/message","data":{"turn":1,"step":4,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{message:9}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[39,40,41,42,43],"surfaceOp":"append"}
-{"type":"tool/call","data":{"turn":1,"step":4,"callId":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\"}"}}
+{"type":"assistant/message","data":{"turn":1,"step":4,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\",\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{message:9}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[39,40,41,42,43],"surfaceOp":"append"}
+{"type":"tool/call","data":{"turn":1,"step":4,"callId":"editor-create","name":"str_replace_editor","arguments":"{\"command\":\"create\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":\"target:\\n\\told\\n\",\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}
 {"type":"tool/result","data":{"turn":1,"step":4,"message":{"source":{"kind":"tool","callId":"editor-create"},"content":[{"type":"tool-result","toolCallId":"editor-create","content":[{"type":"text","text":"New file created successfully at: {{cwd}}/note.txt"}],"isError":false}],"role":"user","id":"{{message:10}}"}},"sourceEventSeqs":[45],"surfaceOp":"append"}
 {"type":"step/end","data":{"turn":1,"step":4}}
 {"type":"step/start","data":{"turn":1,"step":5}}
 {"type":"assistant/chunk","data":{"turn":1,"step":5,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}
-{"type":"assistant/chunk","data":{"turn":1,"step":5,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-view","name":"str_replace_editor","argumentsDelta":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\"}"}}}
-{"type":"assistant/chunk","data":{"turn":1,"step":5,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\"}"}}}}
+{"type":"assistant/chunk","data":{"turn":1,"step":5,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-view","name":"str_replace_editor","argumentsDelta":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":null,\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}
+{"type":"assistant/chunk","data":{"turn":1,"step":5,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":null,\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":5,"chunk":{"type":"usage","usage":{"inputTokens":3,"outputTokens":3}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":5,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
-{"type":"assistant/message","data":{"turn":1,"step":5,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{message:11}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[49,50,51,52,53],"surfaceOp":"append"}
-{"type":"tool/call","data":{"turn":1,"step":5,"callId":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\"}"}}
+{"type":"assistant/message","data":{"turn":1,"step":5,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":null,\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{message:11}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[49,50,51,52,53],"surfaceOp":"append"}
+{"type":"tool/call","data":{"turn":1,"step":5,"callId":"editor-view","name":"str_replace_editor","arguments":"{\"command\":\"view\",\"path\":\"{{cwd}}/note.txt\",\"file_text\":null,\"insert_line\":null,\"new_str\":null,\"old_str\":null,\"view_range\":null}"}}
 {"type":"tool/result","data":{"turn":1,"step":5,"message":{"source":{"kind":"tool","callId":"editor-view"},"content":[{"type":"tool-result","toolCallId":"editor-view","content":[{"type":"text","text":"Here's the content of {{cwd}}/note.txt with line numbers (which has a total of 3 lines):\n     1  target:\n     2  \told\n     3  \n"}],"isError":false}],"role":"user","id":"{{message:12}}"}},"sourceEventSeqs":[55],"surfaceOp":"append"}
 {"type":"step/end","data":{"turn":1,"step":5}}
 {"type":"step/start","data":{"turn":1,"step":6}}
 {"type":"assistant/chunk","data":{"turn":1,"step":6,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}
-{"type":"assistant/chunk","data":{"turn":1,"step":6,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-replace","name":"str_replace_editor","argumentsDelta":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\"}"}}}
-{"type":"assistant/chunk","data":{"turn":1,"step":6,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\"}"}}}}
+{"type":"assistant/chunk","data":{"turn":1,"step":6,"chunk":{"type":"tool-call-delta","index":0,"id":"editor-replace","name":"str_replace_editor","argumentsDelta":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\",\"file_text\":null,\"insert_line\":null,\"view_range\":null}"}}}
+{"type":"assistant/chunk","data":{"turn":1,"step":6,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\",\"file_text\":null,\"insert_line\":null,\"view_range\":null}"}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":6,"chunk":{"type":"usage","usage":{"inputTokens":3,"outputTokens":3}}}}
 {"type":"assistant/chunk","data":{"turn":1,"step":6,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
-{"type":"assistant/message","data":{"turn":1,"step":6,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\"}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{message:13}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[59,60,61,62,63],"surfaceOp":"append"}
-{"type":"tool/call","data":{"turn":1,"step":6,"callId":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\"}"}}
+{"type":"assistant/message","data":{"turn":1,"step":6,"message":{"role":"assistant","content":[{"type":"tool-call","id":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\",\"file_text\":null,\"insert_line\":null,\"view_range\":null}"}],"source":{"kind":"model","provider":"deepseek-official","model":"deepseek-v4-flash"},"id":"{{message:13}}"},"usage":{"inputTokens":3,"outputTokens":3}},"sourceEventSeqs":[59,60,61,62,63],"surfaceOp":"append"}
+{"type":"tool/call","data":{"turn":1,"step":6,"callId":"editor-replace","name":"str_replace_editor","arguments":"{\"command\":\"str_replace\",\"path\":\"{{cwd}}/note.txt\",\"old_str\":\"\\told\",\"new_str\":\"\\tnew\",\"file_text\":null,\"insert_line\":null,\"view_range\":null}"}}
 {"type":"tool/result","data":{"turn":1,"step":6,"message":{"source":{"kind":"tool","callId":"editor-replace"},"content":[{"type":"tool-result","toolCallId":"editor-replace","content":[{"type":"text","text":"The file {{cwd}}/note.txt has been edited successfully."}],"isError":false}],"role":"user","id":"{{message:14}}"}},"sourceEventSeqs":[65],"surfaceOp":"append"}
 {"type":"step/end","data":{"turn":1,"step":6}}
 {"type":"step/start","data":{"turn":1,"step":7}}
diff --git a/snapshots/sdk/persistent-tools/tool-schemas.expected.json b/snapshots/sdk/persistent-tools/tool-schemas.expected.json
index e2fc2b2862..73234c5e49 100644
--- a/snapshots/sdk/persistent-tools/tool-schemas.expected.json
+++ b/snapshots/sdk/persistent-tools/tool-schemas.expected.json
@@ -18,7 +18,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -37,27 +37,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/sdk/subagent-continuable-inheritance/tool-schemas.1.expected.json b/snapshots/sdk/subagent-continuable-inheritance/tool-schemas.1.expected.json
index 62937be9b1..6273e6b106 100644
--- a/snapshots/sdk/subagent-continuable-inheritance/tool-schemas.1.expected.json
+++ b/snapshots/sdk/subagent-continuable-inheritance/tool-schemas.1.expected.json
@@ -392,7 +392,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -411,27 +411,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/sdk/subagent-continuable/tool-schemas.1.expected.json b/snapshots/sdk/subagent-continuable/tool-schemas.1.expected.json
index 62937be9b1..6273e6b106 100644
--- a/snapshots/sdk/subagent-continuable/tool-schemas.1.expected.json
+++ b/snapshots/sdk/subagent-continuable/tool-schemas.1.expected.json
@@ -392,7 +392,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -411,27 +411,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/sdk/subagent-list-agents/tool-schemas.1.expected.json b/snapshots/sdk/subagent-list-agents/tool-schemas.1.expected.json
index 62937be9b1..6273e6b106 100644
--- a/snapshots/sdk/subagent-list-agents/tool-schemas.1.expected.json
+++ b/snapshots/sdk/subagent-list-agents/tool-schemas.1.expected.json
@@ -392,7 +392,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -411,27 +411,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/sdk/subagent-report/tool-schemas.1.expected.json b/snapshots/sdk/subagent-report/tool-schemas.1.expected.json
index 62937be9b1..6273e6b106 100644
--- a/snapshots/sdk/subagent-report/tool-schemas.1.expected.json
+++ b/snapshots/sdk/subagent-report/tool-schemas.1.expected.json
@@ -392,7 +392,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -411,27 +411,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/sdk/text-turn/tool-schemas.expected.json b/snapshots/sdk/text-turn/tool-schemas.expected.json
index 7672d1155f..e8fd1b5981 100644
--- a/snapshots/sdk/text-turn/tool-schemas.expected.json
+++ b/snapshots/sdk/text-turn/tool-schemas.expected.json
@@ -359,7 +359,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -378,27 +378,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/agent-instructions/tool-schemas.expected.json b/snapshots/session/agent-instructions/tool-schemas.expected.json
index 75be989751..0d475b2d80 100644
--- a/snapshots/session/agent-instructions/tool-schemas.expected.json
+++ b/snapshots/session/agent-instructions/tool-schemas.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
@@ -1071,7 +1106,7 @@
       },
       {
         "name": "str_replace_editor",
-        "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+        "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
         "parameters": {
           "type": "object",
           "properties": {
@@ -1090,27 +1125,62 @@
               "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
             },
             "file_text": {
-              "type": "string",
-              "description": "Required parameter of `create` command, with the content of the file to be created."
+              "oneOf": [
+                {
+                  "type": "string"
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
             },
             "insert_line": {
-              "type": "integer",
-              "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+              "oneOf": [
+                {
+                  "type": "integer"
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
             },
             "new_str": {
-              "type": "string",
-              "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+              "oneOf": [
+                {
+                  "type": "string"
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
             },
             "old_str": {
-              "type": "string",
-              "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+              "oneOf": [
+                {
+                  "type": "string"
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
             },
             "view_range": {
-              "type": "array",
-              "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-              "items": {
-                "type": "integer"
-              }
+              "oneOf": [
+                {
+                  "type": "array",
+                  "items": {
+                    "type": "integer"
+                  }
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
             }
           },
           "required": [
diff --git a/snapshots/session/both-mode-turn/system-prompt.expected.md b/snapshots/session/both-mode-turn/system-prompt.expected.md
index 837d449f4a..ba32b06baf 100644
--- a/snapshots/session/both-mode-turn/system-prompt.expected.md
+++ b/snapshots/session/both-mode-turn/system-prompt.expected.md
@@ -174,22 +174,22 @@ interface ToolArgsMap {
     /** The exact skill name from the available skills list. */
     name: string;
   } & Record<string, JsonValue>;
-  /** Custom editing tool for viewing, creating and editing files * State is persistent across command calls and discussions with the user * If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep * The `create` command cannot be used if the specified `path` already exists as a file * If a `command` generates a long output, it will be truncated and marked with `<response clipped>` Notes for using the `str_replace` command: * The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces! * If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique * The `new_str` parameter should contain the edited lines that should replace the `old_str` */
+  /** Custom editing tool for viewing, creating and editing files * State is persistent across command calls and discussions with the user * If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep * The `create` command cannot be used if the specified `path` already exists as a file * If a `command` generates a long output, it will be truncated and marked with `<response clipped>` * A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match Notes for using the `str_replace` command: * The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces! * If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique * The `new_str` parameter should contain the edited lines that should replace the `old_str` */
   str_replace_editor: {
     /** The commands to run. Allowed options are: `view`, `create`, `str_replace`, `insert`. */
     command: "view" | "create" | "str_replace" | "insert";
     /** Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`. */
     path: string;
-    /** Required parameter of `create` command, with the content of the file to be created. */
-    file_text?: string;
-    /** Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. */
-    insert_line?: number;
-    /** Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert. */
-    new_str?: string;
-    /** Required parameter of `str_replace` command containing the string in `path` to replace. */
-    old_str?: string;
-    /** Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file. */
-    view_range?: number[];
+    /** Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    file_text?: string | null;
+    /** Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    insert_line?: number | null;
+    /** Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter. */
+    new_str?: string | null;
+    /** Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    old_str?: string | null;
+    /** Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file. */
+    view_range?: number[] | null;
   } & Record<string, JsonValue>;
   /** Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort. */
   subagent: {
diff --git a/snapshots/session/both-mode-turn/tool-schemas.expected.json b/snapshots/session/both-mode-turn/tool-schemas.expected.json
index bf85198220..5668ee9294 100644
--- a/snapshots/session/both-mode-turn/tool-schemas.expected.json
+++ b/snapshots/session/both-mode-turn/tool-schemas.expected.json
@@ -397,7 +397,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -416,27 +416,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/code-mode-read-image/system-prompt.expected.md b/snapshots/session/code-mode-read-image/system-prompt.expected.md
index 60c5a60aac..1690867b36 100644
--- a/snapshots/session/code-mode-read-image/system-prompt.expected.md
+++ b/snapshots/session/code-mode-read-image/system-prompt.expected.md
@@ -176,22 +176,22 @@ interface ToolArgsMap {
     /** The exact skill name from the available skills list. */
     name: string;
   } & Record<string, JsonValue>;
-  /** Custom editing tool for viewing, creating and editing files * State is persistent across command calls and discussions with the user * If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep * The `create` command cannot be used if the specified `path` already exists as a file * If a `command` generates a long output, it will be truncated and marked with `<response clipped>` Notes for using the `str_replace` command: * The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces! * If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique * The `new_str` parameter should contain the edited lines that should replace the `old_str` */
+  /** Custom editing tool for viewing, creating and editing files * State is persistent across command calls and discussions with the user * If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep * The `create` command cannot be used if the specified `path` already exists as a file * If a `command` generates a long output, it will be truncated and marked with `<response clipped>` * A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match Notes for using the `str_replace` command: * The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces! * If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique * The `new_str` parameter should contain the edited lines that should replace the `old_str` */
   str_replace_editor: {
     /** The commands to run. Allowed options are: `view`, `create`, `str_replace`, `insert`. */
     command: "view" | "create" | "str_replace" | "insert";
     /** Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`. */
     path: string;
-    /** Required parameter of `create` command, with the content of the file to be created. */
-    file_text?: string;
-    /** Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. */
-    insert_line?: number;
-    /** Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert. */
-    new_str?: string;
-    /** Required parameter of `str_replace` command containing the string in `path` to replace. */
-    old_str?: string;
-    /** Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file. */
-    view_range?: number[];
+    /** Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    file_text?: string | null;
+    /** Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    insert_line?: number | null;
+    /** Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter. */
+    new_str?: string | null;
+    /** Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    old_str?: string | null;
+    /** Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file. */
+    view_range?: number[] | null;
   } & Record<string, JsonValue>;
   /** Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort. */
   subagent: {
diff --git a/snapshots/session/code-mode-turn/system-prompt.expected.md b/snapshots/session/code-mode-turn/system-prompt.expected.md
index 2620855beb..ddfe1c8024 100644
--- a/snapshots/session/code-mode-turn/system-prompt.expected.md
+++ b/snapshots/session/code-mode-turn/system-prompt.expected.md
@@ -176,22 +176,22 @@ interface ToolArgsMap {
     /** The exact skill name from the available skills list. */
     name: string;
   } & Record<string, JsonValue>;
-  /** Custom editing tool for viewing, creating and editing files * State is persistent across command calls and discussions with the user * If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep * The `create` command cannot be used if the specified `path` already exists as a file * If a `command` generates a long output, it will be truncated and marked with `<response clipped>` Notes for using the `str_replace` command: * The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces! * If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique * The `new_str` parameter should contain the edited lines that should replace the `old_str` */
+  /** Custom editing tool for viewing, creating and editing files * State is persistent across command calls and discussions with the user * If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep * The `create` command cannot be used if the specified `path` already exists as a file * If a `command` generates a long output, it will be truncated and marked with `<response clipped>` * A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match Notes for using the `str_replace` command: * The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces! * If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique * The `new_str` parameter should contain the edited lines that should replace the `old_str` */
   str_replace_editor: {
     /** The commands to run. Allowed options are: `view`, `create`, `str_replace`, `insert`. */
     command: "view" | "create" | "str_replace" | "insert";
     /** Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`. */
     path: string;
-    /** Required parameter of `create` command, with the content of the file to be created. */
-    file_text?: string;
-    /** Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. */
-    insert_line?: number;
-    /** Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert. */
-    new_str?: string;
-    /** Required parameter of `str_replace` command containing the string in `path` to replace. */
-    old_str?: string;
-    /** Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file. */
-    view_range?: number[];
+    /** Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    file_text?: string | null;
+    /** Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    insert_line?: number | null;
+    /** Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter. */
+    new_str?: string | null;
+    /** Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    old_str?: string | null;
+    /** Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file. */
+    view_range?: number[] | null;
   } & Record<string, JsonValue>;
   /** Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort. */
   subagent: {
diff --git a/snapshots/session/compaction-recovery/tool-schemas.expected.json b/snapshots/session/compaction-recovery/tool-schemas.expected.json
index 75be989751..0d475b2d80 100644
--- a/snapshots/session/compaction-recovery/tool-schemas.expected.json
+++ b/snapshots/session/compaction-recovery/tool-schemas.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
@@ -1071,7 +1106,7 @@
       },
       {
         "name": "str_replace_editor",
-        "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+        "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
         "parameters": {
           "type": "object",
           "properties": {
@@ -1090,27 +1125,62 @@
               "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
             },
             "file_text": {
-              "type": "string",
-              "description": "Required parameter of `create` command, with the content of the file to be created."
+              "oneOf": [
+                {
+                  "type": "string"
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
             },
             "insert_line": {
-              "type": "integer",
-              "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+              "oneOf": [
+                {
+                  "type": "integer"
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
             },
             "new_str": {
-              "type": "string",
-              "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+              "oneOf": [
+                {
+                  "type": "string"
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
             },
             "old_str": {
-              "type": "string",
-              "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+              "oneOf": [
+                {
+                  "type": "string"
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
             },
             "view_range": {
-              "type": "array",
-              "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-              "items": {
-                "type": "integer"
-              }
+              "oneOf": [
+                {
+                  "type": "array",
+                  "items": {
+                    "type": "integer"
+                  }
+                },
+                {
+                  "type": "null"
+                }
+              ],
+              "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
             }
           },
           "required": [
diff --git a/snapshots/session/cordis-inspect-jsdoc/system-prompt.expected.md b/snapshots/session/cordis-inspect-jsdoc/system-prompt.expected.md
index 7279b7ace3..a0dfdc2277 100644
--- a/snapshots/session/cordis-inspect-jsdoc/system-prompt.expected.md
+++ b/snapshots/session/cordis-inspect-jsdoc/system-prompt.expected.md
@@ -341,22 +341,22 @@ interface ToolArgsMap {
     /** The exact skill name from the available skills list. */
     name: string;
   } & Record<string, JsonValue>;
-  /** Custom editing tool for viewing, creating and editing files * State is persistent across command calls and discussions with the user * If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep * The `create` command cannot be used if the specified `path` already exists as a file * If a `command` generates a long output, it will be truncated and marked with `<response clipped>` Notes for using the `str_replace` command: * The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces! * If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique * The `new_str` parameter should contain the edited lines that should replace the `old_str` */
+  /** Custom editing tool for viewing, creating and editing files * State is persistent across command calls and discussions with the user * If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep * The `create` command cannot be used if the specified `path` already exists as a file * If a `command` generates a long output, it will be truncated and marked with `<response clipped>` * A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match Notes for using the `str_replace` command: * The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces! * If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique * The `new_str` parameter should contain the edited lines that should replace the `old_str` */
   str_replace_editor: {
     /** The commands to run. Allowed options are: `view`, `create`, `str_replace`, `insert`. */
     command: "view" | "create" | "str_replace" | "insert";
     /** Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`. */
     path: string;
-    /** Required parameter of `create` command, with the content of the file to be created. */
-    file_text?: string;
-    /** Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. */
-    insert_line?: number;
-    /** Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert. */
-    new_str?: string;
-    /** Required parameter of `str_replace` command containing the string in `path` to replace. */
-    old_str?: string;
-    /** Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file. */
-    view_range?: number[];
+    /** Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    file_text?: string | null;
+    /** Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    insert_line?: number | null;
+    /** Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter. */
+    new_str?: string | null;
+    /** Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter. */
+    old_str?: string | null;
+    /** Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file. */
+    view_range?: number[] | null;
   } & Record<string, JsonValue>;
   /** Delegate a self-contained task to a subagent (a separate agent that works in its own context) to offload focused, independent work — research, a scoped implementation, an analysis — so it does not consume this conversation's context. The subagent returns its result, not its intermediate steps. Give it a complete, standalone prompt: it does not see this conversation. This tool runs in the background by default, immediately returns a durable subagent id, and keeps the child conversation available for later turns. When that run settles, the runtime sends the parent a notice containing its outcome and any final assistant message; `send_message` starts a later turn in the same child conversation. Set `run_in_background: false` only when your next action depends on receiving the result. Child LLM selection is optional. Omit `provider`, `model`, and `reasoning_effort` to use configured child defaults and inherit compatible missing values from the parent Agent. Supply `provider` and `model` together after using `list_subagent_models` to inspect advertised routes and efforts. Changing the effective route without naming an effort uses the selected model's default effort. */
   subagent: {
diff --git a/snapshots/session/cordis-inspect-jsdoc/tool-schemas.expected.json b/snapshots/session/cordis-inspect-jsdoc/tool-schemas.expected.json
index 2f1950a691..9faf8c3d89 100644
--- a/snapshots/session/cordis-inspect-jsdoc/tool-schemas.expected.json
+++ b/snapshots/session/cordis-inspect-jsdoc/tool-schemas.expected.json
@@ -594,7 +594,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -613,27 +613,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/fs-glob-sampling/tool-schemas.expected.json b/snapshots/session/fs-glob-sampling/tool-schemas.expected.json
index 2819e54870..4f943e54bf 100644
--- a/snapshots/session/fs-glob-sampling/tool-schemas.expected.json
+++ b/snapshots/session/fs-glob-sampling/tool-schemas.expected.json
@@ -280,7 +280,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -299,27 +299,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/lsp-definition/tool-schemas.expected.json b/snapshots/session/lsp-definition/tool-schemas.expected.json
index c012852f0a..818a268882 100644
--- a/snapshots/session/lsp-definition/tool-schemas.expected.json
+++ b/snapshots/session/lsp-definition/tool-schemas.expected.json
@@ -413,7 +413,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -432,27 +432,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/product-subagent-both/tool-schemas.expected.json b/snapshots/session/product-subagent-both/tool-schemas.expected.json
index 5eec9bb706..fe34e29475 100644
--- a/snapshots/session/product-subagent-both/tool-schemas.expected.json
+++ b/snapshots/session/product-subagent-both/tool-schemas.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/product-subagent-codex/tool-schemas.expected.json b/snapshots/session/product-subagent-codex/tool-schemas.expected.json
index 2d5b27c48b..5efa018df1 100644
--- a/snapshots/session/product-subagent-codex/tool-schemas.expected.json
+++ b/snapshots/session/product-subagent-codex/tool-schemas.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/product-subagent-result-diagnostic/tool-schemas.expected.json b/snapshots/session/product-subagent-result-diagnostic/tool-schemas.expected.json
index bb5b4b7411..6752716683 100644
--- a/snapshots/session/product-subagent-result-diagnostic/tool-schemas.expected.json
+++ b/snapshots/session/product-subagent-result-diagnostic/tool-schemas.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/pty-tools-sandbox-backend/tool-schemas.expected.json b/snapshots/session/pty-tools-sandbox-backend/tool-schemas.expected.json
index 2303325732..7714ecf3a5 100644
--- a/snapshots/session/pty-tools-sandbox-backend/tool-schemas.expected.json
+++ b/snapshots/session/pty-tools-sandbox-backend/tool-schemas.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/ralph-loop/tool-schemas.1.expected.json b/snapshots/session/ralph-loop/tool-schemas.1.expected.json
index 4183c61b3d..54d0732db7 100644
--- a/snapshots/session/ralph-loop/tool-schemas.1.expected.json
+++ b/snapshots/session/ralph-loop/tool-schemas.1.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/ralph-loop/tool-schemas.2.expected.json b/snapshots/session/ralph-loop/tool-schemas.2.expected.json
index 4183c61b3d..54d0732db7 100644
--- a/snapshots/session/ralph-loop/tool-schemas.2.expected.json
+++ b/snapshots/session/ralph-loop/tool-schemas.2.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/session-query-spill/tool-schemas.expected.json b/snapshots/session/session-query-spill/tool-schemas.expected.json
index 7ff41194b3..62b603d80c 100644
--- a/snapshots/session/session-query-spill/tool-schemas.expected.json
+++ b/snapshots/session/session-query-spill/tool-schemas.expected.json
@@ -580,7 +580,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -599,27 +599,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/subagent-acp-diagnostic/tool-schemas.expected.json b/snapshots/session/subagent-acp-diagnostic/tool-schemas.expected.json
index 3989c7d529..2f46955ebd 100644
--- a/snapshots/session/subagent-acp-diagnostic/tool-schemas.expected.json
+++ b/snapshots/session/subagent-acp-diagnostic/tool-schemas.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/subagent-child-question-rejection/tool-schemas.expected.json b/snapshots/session/subagent-child-question-rejection/tool-schemas.expected.json
index 6aa10aa7d5..76f213f7c8 100644
--- a/snapshots/session/subagent-child-question-rejection/tool-schemas.expected.json
+++ b/snapshots/session/subagent-child-question-rejection/tool-schemas.expected.json
@@ -439,7 +439,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -458,27 +458,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/text-turn/tool-schemas.expected.json b/snapshots/session/text-turn/tool-schemas.expected.json
index 0720890967..4922f06fdf 100644
--- a/snapshots/session/text-turn/tool-schemas.expected.json
+++ b/snapshots/session/text-turn/tool-schemas.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/session/web-fetch/tool-schemas.expected.json b/snapshots/session/web-fetch/tool-schemas.expected.json
index 630a9b086f..85c8e3bf4a 100644
--- a/snapshots/session/web-fetch/tool-schemas.expected.json
+++ b/snapshots/session/web-fetch/tool-schemas.expected.json
@@ -376,7 +376,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -395,27 +395,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [
diff --git a/snapshots/web/minimal-preset/tool-schemas.expected.json b/snapshots/web/minimal-preset/tool-schemas.expected.json
index e2fc2b2862..73234c5e49 100644
--- a/snapshots/web/minimal-preset/tool-schemas.expected.json
+++ b/snapshots/web/minimal-preset/tool-schemas.expected.json
@@ -18,7 +18,7 @@
     },
     {
       "name": "str_replace_editor",
-      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
+      "description": "Custom editing tool for viewing, creating and editing files\n* State is persistent across command calls and discussions with the user\n* If `path` is a file, `view` displays the result of applying `cat -n`. If `path` is a directory, `view` lists non-hidden files and directories up to 2 levels deep\n* The `create` command cannot be used if the specified `path` already exists as a file\n* If a `command` generates a long output, it will be truncated and marked with `<response clipped>`\n* A null placeholder for a parameter unused by the selected command is treated as omitted. Required parameters still need values; omit `str_replace.new_str` rather than setting it to null when deleting a match\n\nNotes for using the `str_replace` command:\n* The `old_str` parameter should match EXACTLY one or more consecutive lines from the original file. Be mindful of whitespaces!\n* If the `old_str` parameter is not unique in the file, the replacement will not be performed. Make sure to include enough context in `old_str` to make it unique\n* The `new_str` parameter should contain the edited lines that should replace the `old_str`",
       "parameters": {
         "type": "object",
         "properties": {
@@ -37,27 +37,62 @@
             "description": "Absolute path to file or directory, e.g. `/repo/file.py` or `/repo`."
           },
           "file_text": {
-            "type": "string",
-            "description": "Required parameter of `create` command, with the content of the file to be created."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `create` command, with the content of the file to be created. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "insert_line": {
-            "type": "integer",
-            "description": "Required parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`."
+            "oneOf": [
+              {
+                "type": "integer"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required integer parameter of `insert` command. The `new_str` will be inserted AFTER the line `insert_line` of `path`. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "new_str": {
-            "type": "string",
-            "description": "Optional parameter of `str_replace` command containing the new string (if not given, no string will be added). Required parameter of `insert` command containing the string to insert."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional string parameter of `str_replace` command containing the new string (if omitted, no string will be added). Required string parameter of `insert` command containing the string to insert. A null placeholder is accepted only by commands that do not use this parameter."
           },
           "old_str": {
-            "type": "string",
-            "description": "Required parameter of `str_replace` command containing the string in `path` to replace."
+            "oneOf": [
+              {
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Required string parameter of `str_replace` command containing the string in `path` to replace. A null placeholder is treated as omitted by commands that do not use this parameter."
           },
           "view_range": {
-            "type": "array",
-            "description": "Optional parameter of `view` command when `path` points to a file. If none is given, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file.",
-            "items": {
-              "type": "integer"
-            }
+            "oneOf": [
+              {
+                "type": "array",
+                "items": {
+                  "type": "integer"
+                }
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Optional parameter of `view` command when `path` points to a file. If omitted or null, the full file is shown. If provided, the file will be shown in the indicated line number range, e.g. [11, 12] will show lines 11 and 12. Indexing at 1 to start. Setting `[start_line, -1]` shows all lines from `start_line` to the end of the file."
           }
         },
         "required": [