{"meta":{"title":"工具使用前挂钩","intro":"在 onPreToolUse 工具执行 之前 调用挂钩。 使用它可执行以下操作：","product":"GitHub Copilot","breadcrumbs":[{"href":"/zh/copilot","title":"GitHub Copilot"},{"href":"/zh/copilot/how-tos","title":"操作方法"},{"href":"/zh/copilot/how-tos/copilot-sdk","title":"Copilot SDK"},{"href":"/zh/copilot/how-tos/copilot-sdk/hooks","title":"使用挂钩"},{"href":"/zh/copilot/how-tos/copilot-sdk/hooks/pre-tool-use","title":"使用工具前"}],"documentType":"article"},"body":"# 工具使用前挂钩\n\n在 onPreToolUse 工具执行 之前 调用挂钩。 使用它可执行以下操作：\n\n\n\n\n\n* 批准或拒绝工具执行\n* 修改工具参数\n* 添加工具的上下文\n* 取消对话中的工具输出\n\n## 挂钩签名\n\n
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TypeScript
\n\n```typescript\ntype PreToolUseHandler = (\n input: PreToolUseHookInput,\n invocation: HookInvocation\n) => Promise;\n```\n\n
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Python
\n\n```python\nPreToolUseHandler = Callable[\n [PreToolUseHookInput, dict[str, str]],\n Awaitable[PreToolUseHookOutput | None]\n]\n```\n\n
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Go
\n\n```golang\ntype PreToolUseHandler func(\n input PreToolUseHookInput,\n invocation HookInvocation,\n) (*PreToolUseHookOutput, error)\n```\n\n
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.NET
\n\n```csharp\npublic delegate Task PreToolUseHandler(\n PreToolUseHookInput input,\n HookInvocation invocation);\n```\n\n
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Java
\n\n```java\n@FunctionalInterface\npublic interface PreToolUseHandler {\n CompletableFuture handle(\n PreToolUseHookInput input,\n HookInvocation invocation);\n}\n```\n\n
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\n\n## 输入\n\n| 领域 | 类型 | Description |\n| ----------- | ------ | --------------- |\n| `timestamp` | number | 触发挂钩时的 Unix 时间戳 |\n| `cwd` | 字符串 | 当前工作目录 |\n| `toolName` | 字符串 | 要调用的工具的名称 |\n| `toolArgs` | 对象 | 传递给工具的参数 |\n\n## 输出\n\n返回 `null` 或 `undefined` 允许工具执行，无需更改。 否则，返回包含以下任何字段的对象：\n\n| 领域 | 类型 | Description |\n| -------------------------- | ------- | ---------------------- |\n| `permissionDecision` | | |\n| `\"allow\"` | | |\n| \\| | | |\n| `\"deny\"` | | |\n| \\| | | |\n| `\"ask\"` | | |\n| 是否允许工具调用 | | |\n| `permissionDecisionReason` | 字符串 | 向用户显示的说明（用于拒绝/询问） |\n| `modifiedArgs` | 对象 | 传递给工具的已修改参数 |\n| `additionalContext` | 字符串 | 向对话注入额外上下文 |\n| `suppressOutput` | boolean | 如果为 true，工具输出将不会显示在对话中 |\n\n### 权限决策\n\n| 决策 | Behavior |\n| --------- | --------------- |\n| `\"allow\"` | 工具正常执行 |\n| `\"deny\"` | 工具被阻止，原因会显示给用户。 |\n| `\"ask\"` | 系统会提示用户批准（交互模式） |\n\n### 跳过受信任的自定义工具的权限提示\n\n如果你定义了一个无需提示即可安全运行的自定义工具，请在工具定义中设置 `skipPermission: true`。 将其用于受信任的应用自有工具，这些工具的输入已由应用程序加以约束；当需要进行逐次调用的策略检查或参数验证时，请使用 `onPreToolUse`。\n\n```typescript\nconst getWeather = defineTool(\"get_weather\", {\n description: \"Get weather for a location.\",\n parameters: {\n type: \"object\",\n properties: { location: { type: \"string\" } },\n required: [\"location\"],\n },\n skipPermission: true,\n handler: async ({ location }) => ({ forecast: `Sunny in ${location}` }),\n});\n```\n\n## 示例\n\n### 允许所有工具（仅限日志记录）\n\n
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TypeScript
\n\n```typescript\nconst session = await client.createSession({\n hooks: {\n onPreToolUse: async (input, invocation) => {\n console.log(`[${invocation.sessionId}] Calling ${input.toolName}`);\n console.log(` Args: ${JSON.stringify(input.toolArgs)}`);\n return { permissionDecision: \"allow\" };\n },\n },\n});\n```\n\n
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Python
\n\n```python\nfrom copilot.session import PermissionHandler\n\nasync def on_pre_tool_use(input_data, invocation):\n print(f\"[{invocation['session_id']}] Calling {input_data['toolName']}\")\n print(f\" Args: {input_data['toolArgs']}\")\n return {\"permissionDecision\": \"allow\"}\n\nsession = await client.create_session(on_permission_request=PermissionHandler.approve_all, hooks={\"on_pre_tool_use\": on_pre_tool_use})\n```\n\n
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Go
\n\n```golang\nsession, _ := client.CreateSession(context.Background(), &copilot.SessionConfig{\n Hooks: &copilot.SessionHooks{\n OnPreToolUse: func(input copilot.PreToolUseHookInput, inv copilot.HookInvocation) (*copilot.PreToolUseHookOutput, error) {\n fmt.Printf(\"[%s] Calling %s\\n\", inv.SessionID, input.ToolName)\n fmt.Printf(\" Args: %v\\n\", input.ToolArgs)\n return &copilot.PreToolUseHookOutput{\n PermissionDecision: \"allow\",\n }, nil\n },\n },\n})\n```\n\n
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.NET
\n\n```csharp\nvar session = await client.CreateSessionAsync(new SessionConfig\n{\n Hooks = new SessionHooks\n {\n OnPreToolUse = (input, invocation) =>\n {\n Console.WriteLine($\"[{invocation.SessionId}] Calling {input.ToolName}\");\n Console.WriteLine($\" Args: {input.ToolArgs}\");\n return Task.FromResult(\n new PreToolUseHookOutput { PermissionDecision = \"allow\" }\n );\n },\n },\n});\n```\n\n
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Java
\n\n\n\n```java\nimport com.github.copilot.*;\nimport com.github.copilot.rpc.*;\nimport java.util.concurrent.CompletableFuture;\n\nvar hooks = new SessionHooks()\n .setOnPreToolUse((input, invocation) -> {\n System.out.println(\"[\" + invocation.getSessionId() + \"] Calling \" + input.getToolName());\n System.out.println(\" Args: \" + input.getToolArgs());\n return CompletableFuture.completedFuture(PreToolUseHookOutput.allow());\n });\n\nvar session = client.createSession(\n new SessionConfig()\n .setOnPermissionRequest(PermissionHandler.APPROVE_ALL)\n .setHooks(hooks)\n).get();\n```\n\n
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\n\n### 阻止特定工具\n\n```typescript\nconst BLOCKED_TOOLS = [\"shell\", \"bash\", \"write_file\", \"delete_file\"];\n\nconst session = await client.createSession({\n hooks: {\n onPreToolUse: async (input) => {\n if (BLOCKED_TOOLS.includes(input.toolName)) {\n return {\n permissionDecision: \"deny\",\n permissionDecisionReason: `Tool '${input.toolName}' is not permitted in this environment`,\n };\n }\n return { permissionDecision: \"allow\" };\n },\n },\n});\n```\n\n### 修改工具参数\n\n```typescript\nconst session = await client.createSession({\n hooks: {\n onPreToolUse: async (input) => {\n // Add a default timeout to all shell commands\n if (input.toolName === \"shell\" && input.toolArgs) {\n const args = input.toolArgs as { command: string; timeout?: number };\n return {\n permissionDecision: \"allow\",\n modifiedArgs: {\n ...args,\n timeout: args.timeout ?? 30000, // Default 30s timeout\n },\n };\n }\n return { permissionDecision: \"allow\" };\n },\n },\n});\n```\n\n### 限制对特定目录的文件访问\n\n```typescript\nconst ALLOWED_DIRECTORIES = [\"/home/user/projects\", \"/tmp\"];\n\nconst session = await client.createSession({\n hooks: {\n onPreToolUse: async (input) => {\n if (input.toolName === \"read_file\" || input.toolName === \"write_file\") {\n const args = input.toolArgs as { path: string };\n const isAllowed = ALLOWED_DIRECTORIES.some(dir => \n args.path.startsWith(dir)\n );\n \n if (!isAllowed) {\n return {\n permissionDecision: \"deny\",\n permissionDecisionReason: `Access to '${args.path}' is not permitted. Allowed directories: ${ALLOWED_DIRECTORIES.join(\", \")}`,\n };\n }\n }\n return { permissionDecision: \"allow\" };\n },\n },\n});\n```\n\n### 抑制冗长工具输出\n\n```typescript\nconst VERBOSE_TOOLS = [\"list_directory\", \"search_files\"];\n\nconst session = await client.createSession({\n hooks: {\n onPreToolUse: async (input) => {\n return {\n permissionDecision: \"allow\",\n suppressOutput: VERBOSE_TOOLS.includes(input.toolName),\n };\n },\n },\n});\n```\n\n### 根据工具添加上下文\n\n```typescript\nconst session = await client.createSession({\n hooks: {\n onPreToolUse: async (input) => {\n if (input.toolName === \"query_database\") {\n return {\n permissionDecision: \"allow\",\n additionalContext: \"Remember: This database uses PostgreSQL syntax. Always use parameterized queries.\",\n };\n }\n return { permissionDecision: \"allow\" };\n },\n },\n});\n```\n\n## 最佳做法\n\n1. **始终返回一个决策** - 返回 `null` 即可允许该工具，但若明确返回 `{ permissionDecision: \"allow\" }` 会更清晰。\n\n2. **提供有用的拒绝原因** - 拒绝时，请解释用户理解的原因：\n\n ```typescript\n return {\n permissionDecision: \"deny\",\n permissionDecisionReason: \"Shell commands require approval. Please describe what you want to accomplish.\",\n };\n ```\n\n3. **请谨慎修改参数** - 确保修改后的参数维护工具的预期架构。\n\n4. **考虑性能** - 工具调用前钩子会在每次工具调用之前同步运行。 保持快速。\n\n5. **谨慎使用 `suppressOutput`** - 抑制输出意味着模型看不到结果，这可能会影响聊天质量。\n\n## 另见\n\n* [使用挂钩](/zh/copilot/how-tos/copilot-sdk/hooks)\n* [工具使用后挂钩](/zh/copilot/how-tos/copilot-sdk/hooks/post-tool-use)\n* [调试指南](/zh/copilot/how-tos/copilot-sdk/troubleshooting/debugging)"}