# Tool Registration

## Interface

```typescript
// Without agent context
api.registerTool({
  name: "my-tool",
  description: "Does something",
  inputSchema: {
    type: "object",
    properties: {
      param: { type: "string", description: "..." },
    },
    required: ["param"],
  },
  execute: async (toolCallId, params) => {
    const { param } = params as { param: string };
    return { result: "ok" };
  },
});

// With agent context (factory function)
api.registerTool((ctx) => ({
  name: "my-contextual-tool",
  description: "...",
  inputSchema: { /* ... */ },
  execute: async (toolCallId, params) => {
    const agentId = ctx.agentId;
    return { result: agentId };
  },
}));
```

## Key Points

- Interface is `execute: async (toolCallId, params)`, NOT `handler:`
- Use `inputSchema` (JSON Schema), NOT `parameters`
- Return `{ result: "..." }` object
- Factory form `(ctx) => ({...})` gives access to agent context (agentId, sessionKey, etc.)