> ## Documentation Index
> Fetch the complete documentation index at: https://docs.wandb.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# startSubagent

> TypeScript SDK reference

# startSubagent

▸ **startSubagent**(`opts`): [`SubAgent`](../classes/subagent)

Start a SubAgent span. Same parent-resolution rules as `startTool`.

#### Parameters

| Name   | Type                                         |
| :----- | :------------------------------------------- |
| `opts` | [`SubAgentInit`](../interfaces/subagentinit) |

#### Returns

[`SubAgent`](../classes/subagent)

`Example`

```ts twoslash theme={null}
// @noErrors
weave.startSubagent({name: 'critic'});
```

`Example`

```ts twoslash theme={null}
// @noErrors
weave.startSubagent({
  name: 'critic',
  model: 'gpt-4o',
  systemInstructions: ['Critique the proposed plan.'],
  startTime: new Date('2026-05-29T10:00:00.000Z'),
});
```

#### Defined in

[src/genai/api.ts:137](https://github.com/wandb/weave/blob/8c5f077eb11c42b84000726ff20504abc728d3fb/sdks/node/src/genai/api.ts#L137)

***