> ## Documentation Index
> Fetch the complete documentation index at: https://wb-21fd5541-docs-2516.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# SubAgent

> TypeScript SDK reference

export const GitHubLink = ({url, compact = false}) => <a href={url} target="_blank" rel="noopener noreferrer" className={compact ? "source-link" : "github-source-link"}>
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<GitHubLink url="https://github.com/wandb/weave/blob/7c9efdc9fe05ffcaf2430dd652ef9bc5b3ffdfaa/sdks/node/src/genai/subagent.ts#L84" />

## Extends

* `SpanBase`

## Accessors

### model

#### Get Signature

> **get** **model**(): `string`

##### Returns

`string`

***

### name

#### Get Signature

> **get** **name**(): `string`

##### Returns

`string`

## Methods

### ~~addEvent()~~

<Warning>
  **Deprecated.** Record this data via [setAttributes](#setattributes) instead.
  OpenTelemetry is phasing out the Span Event API (`Span.addEvent`). This
  method still works and existing span-event data stays valid.
  See [https://opentelemetry.io/blog/2026/deprecating-span-events/](https://opentelemetry.io/blog/2026/deprecating-span-events/)
</Warning>

> **addEvent**(`name`, `attributes?`, `startTime?`): `this`

Add a named event to the span. Useful for marking non-span moments such as
context compaction, tool-loop detection, or guardrail trips. Warns and
no-ops after `end()`. Mirrors OTel `Span.addEvent`.

#### Parameters

<ParamField path="name" type="string" required />

<ParamField path="attributes" type="Attributes" />

<ParamField path="startTime" type="TimeInput" />

#### Returns

`this`

#### Example

```ts twoslash theme={null}
// @noErrors
span.addEvent('context_compacted', {removedMessages: 12});
```

#### Inherited from

`SpanBase.addEvent`

***

### end()

> **end**(`opts?`): `void`

Read current field values (to reflect mutations made via `record()`
since `start`) and close the span. Idempotent. Pass `error` to mark
it as failed; pass `endTime` to backdate the close.

#### Parameters

<ParamField path="opts" type="object">
  <Expandable title="properties" defaultOpen>
    <ParamField path="endTime" type="TimeInput" />

    <ParamField path="error" type="Error" />
  </Expandable>
</ParamField>

#### Returns

`void`

***

### record()

> **record**(`opts`): `this`

Bulk-set any subset of the mutable fields. Replaces (does not merge).
Input and output messages are serialized when the span ends.

#### Parameters

<ParamField path="opts" type="object" required>
  <Expandable title="properties" defaultOpen>
    <ParamField path="agentDescription" type="string" />

    <ParamField path="agentId" type="string" />

    <ParamField path="agentVersion" type="string" />

    <ParamField path="messages" type="Message[]">
      See [`Message`](./message).
    </ParamField>

    <ParamField path="model" type="string" />

    <ParamField path="name" type="string" />

    <ParamField path="outputMessages" type="Message[]">
      See [`Message`](./message).
    </ParamField>

    <ParamField path="systemInstructions" type="string[]" />
  </Expandable>
</ParamField>

#### Returns

`this`

***

### setAttributes()

> **setAttributes**(`attributes`): `this`

Set multiple attributes on the span at once. Warns and no-ops after
`end()`. Mirrors OTel `Span.setAttributes` (and the Python SDK's
`set_attributes`).

#### Parameters

<ParamField path="attributes" type="Attributes" required />

#### Returns

`this`

#### Example

```ts twoslash theme={null}
// @noErrors
span.setAttributes({'weave.tag': 'prod', 'gen_ai.response.id': id});
```

#### Inherited from

`SpanBase.setAttributes`

***

### startLLM()

> **startLLM**(`opts`): [`LLM`](./llm)

Start a child LLM span nested under this SubAgent.

#### Parameters

<ParamField path="opts" type="LLMInit" required>
  See [`LLMInit`](./llminit).
</ParamField>

#### Returns

[`LLM`](./llm)

***

### startSubagent()

> **startSubagent**(`opts`): `SubAgent`

Start a nested SubAgent span under this SubAgent.

#### Parameters

<ParamField path="opts" type="SubAgentInit" required>
  See [`SubAgentInit`](./subagentinit).
</ParamField>

#### Returns

`SubAgent`

***

### startTool()

> **startTool**(`opts`): [`Tool`](./tool)

Start a child Tool span nested under this SubAgent.

#### Parameters

<ParamField path="opts" type="ToolInit" required>
  See [`ToolInit`](./toolinit).
</ParamField>

#### Returns

[`Tool`](./tool)