TypeScript
```typescript
type PreToolUseHandler = (
input: PreToolUseHookInput,
invocation: HookInvocation
) => Promise
;
```
Python
```python
PreToolUseHandler = Callable[
[PreToolUseHookInput, dict[str, str]],
Awaitable[PreToolUseHookOutput | None]
]
```
Go
```golang
type PreToolUseHandler func(
input PreToolUseHookInput,
invocation HookInvocation,
) (*PreToolUseHookOutput, error)
```
.NET
```csharp
public delegate Task
PreToolUseHandler(
PreToolUseHookInput input,
HookInvocation invocation);
```
Java
```java
@FunctionalInterface
public interface PreToolUseHandler {
CompletableFuture
handle(
PreToolUseHookInput input,
HookInvocation invocation);
}
```
## 输入
| 领域 | 类型 | Description |
| ----------- | ------ | --------------- |
| `timestamp` | number | 触发挂钩时的 Unix 时间戳 |
| `cwd` | 字符串 | 当前工作目录 |
| `toolName` | 字符串 | 要调用的工具的名称 |
| `toolArgs` | 对象 | 传递给工具的参数 |
## 输出
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：
| 领域 | 类型 | Description |
| -------------------------- | ------- | ---------------------- |
| `permissionDecision` | | |
| `"allow"` | | |
| \| | | |
| `"deny"` | | |
| \| | | |
| `"ask"` | | |
| 是否允许工具调用 | | |
| `permissionDecisionReason` | 字符串 | 向用户显示的说明（用于拒绝/询问） |
| `modifiedArgs` | 对象 | 传递给工具的已修改参数 |
| `additionalContext` | 字符串 | 向对话注入额外上下文 |
| `suppressOutput` | boolean | 如果为 true，工具输出将不会显示在对话中 |
### 权限决策
| 决策 | Behavior |
| --------- | --------------- |
| `"allow"` | 工具正常执行 |
| `"deny"` | 工具被阻止，原因会显示给用户。 |
| `"ask"` | 系统会提示用户批准（交互模式） |
### 跳过受信任的自定义工具的权限提示
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`。
```typescript
const getWeather = defineTool("get_weather", {
description: "Get weather for a location.",
parameters: {
type: "object",
properties: { location: { type: "string" } },
required: ["location"],
},
skipPermission: true,
handler: async ({ location }) => ({ forecast: `Sunny in ${location}` }),
});
```
## 示例
### 允许所有工具（仅限日志记录）
TypeScript
```typescript
const session = await client.createSession({
hooks: {
onPreToolUse: async (input, invocation) => {
console.log(`[${invocation.sessionId}] Calling ${input.toolName}`);
console.log(` Args: ${JSON.stringify(input.toolArgs)}`);
return { permissionDecision: "allow" };
},
},
});
```
Python
```python
from copilot.session import PermissionHandler
async def on_pre_tool_use(input_data, invocation):
print(f"[{invocation['session_id']}] Calling {input_data['toolName']}")
print(f" Args: {input_data['toolArgs']}")
return {"permissionDecision": "allow"}
session = await client.create_session(on_permission_request=PermissionHandler.approve_all, hooks={"on_pre_tool_use": on_pre_tool_use})
```
Go
```golang
session, _ := client.CreateSession(context.Background(), &copilot.SessionConfig{
Hooks: &copilot.SessionHooks{
OnPreToolUse: func(input copilot.PreToolUseHookInput, inv copilot.HookInvocation) (*copilot.PreToolUseHookOutput, error) {
fmt.Printf("[%s] Calling %s\n", inv.SessionID, input.ToolName)
fmt.Printf(" Args: %v\n", input.ToolArgs)
return &copilot.PreToolUseHookOutput{
PermissionDecision: "allow",
}, nil
},
},
})
```
.NET
```csharp
var session = await client.CreateSessionAsync(new SessionConfig
{
Hooks = new SessionHooks
{
OnPreToolUse = (input, invocation) =>
{
Console.WriteLine($"[{invocation.SessionId}] Calling {input.ToolName}");
Console.WriteLine($" Args: {input.ToolArgs}");
return Task.FromResult
(
new PreToolUseHookOutput { PermissionDecision = "allow" }
);
},
},
});
```
Java
```java
import com.github.copilot.*;
import com.github.copilot.rpc.*;
import java.util.concurrent.CompletableFuture;
var hooks = new SessionHooks()
.setOnPreToolUse((input, invocation) -> {
System.out.println("[" + invocation.getSessionId() + "] Calling " + input.getToolName());
System.out.println(" Args: " + input.getToolArgs());
return CompletableFuture.completedFuture(PreToolUseHookOutput.allow());
});
var session = client.createSession(
new SessionConfig()
.setOnPermissionRequest(PermissionHandler.APPROVE_ALL)
.setHooks(hooks)
).get();
```
### 阻止特定工具
```typescript
const BLOCKED_TOOLS = ["shell", "bash", "write_file", "delete_file"];
const session = await client.createSession({
hooks: {
onPreToolUse: async (input) => {
if (BLOCKED_TOOLS.includes(input.toolName)) {
return {
permissionDecision: "deny",
permissionDecisionReason: `Tool '${input.toolName}' is not permitted in this environment`,
};
}
return { permissionDecision: "allow" };
},
},
});
```
### 修改工具参数
```typescript
const session = await client.createSession({
hooks: {
onPreToolUse: async (input) => {
// Add a default timeout to all shell commands
if (input.toolName === "shell" && input.toolArgs) {
const args = input.toolArgs as { command: string; timeout?: number };
return {
permissionDecision: "allow",
modifiedArgs: {
...args,
timeout: args.timeout ?? 30000, // Default 30s timeout
},
};
}
return { permissionDecision: "allow" };
},
},
});
```
### 限制对特定目录的文件访问
```typescript
const ALLOWED_DIRECTORIES = ["/home/user/projects", "/tmp"];
const session = await client.createSession({
hooks: {
onPreToolUse: async (input) => {
if (input.toolName === "read_file" || input.toolName === "write_file") {
const args = input.toolArgs as { path: string };
const isAllowed = ALLOWED_DIRECTORIES.some(dir =>
args.path.startsWith(dir)
);
if (!isAllowed) {
return {
permissionDecision: "deny",
permissionDecisionReason: `Access to '${args.path}' is not permitted. Allowed directories: ${ALLOWED_DIRECTORIES.join(", ")}`,
};
}
}
return { permissionDecision: "allow" };
},
},
});
```
### 抑制冗长工具输出
```typescript
const VERBOSE_TOOLS = ["list_directory", "search_files"];
const session = await client.createSession({
hooks: {
onPreToolUse: async (input) => {
return {
permissionDecision: "allow",
suppressOutput: VERBOSE_TOOLS.includes(input.toolName),
};
},
},
});
```
### 根据工具添加上下文
```typescript
const session = await client.createSession({
hooks: {
onPreToolUse: async (input) => {
if (input.toolName === "query_database") {
return {
permissionDecision: "allow",
additionalContext: "Remember: This database uses PostgreSQL syntax. Always use parameterized queries.",
};
}
return { permissionDecision: "allow" };
},
},
});
```
## 最佳做法
1. **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。
2. **提供有用的拒绝原因** - 拒绝时，请解释用户理解的原因：
```typescript
return {
permissionDecision: "deny",
permissionDecisionReason: "Shell commands require approval. Please describe what you want to accomplish.",
};
```
3. **请谨慎修改参数** - 确保修改后的参数维护工具的预期架构。
4. **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。
5. **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。
## 另见
* [使用挂钩](/zh/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks)
* [工具使用后挂钩](/zh/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/hooks/post-tool-use)
* [调试指南](/zh/enterprise-cloud@latest/copilot/how-tos/copilot-sdk/troubleshooting/debugging)