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

# Mark First Token • Rust AI Agent SDK

> mark_first_token: Mark first token

# mark\_first\_token

<div className="flex items-center gap-2">
  <Badge color="purple">Method</Badge>
</div>

> This is a method of the [**StreamMetrics**](../classes/StreamMetrics) class in the [**streaming**](../modules/streaming) module.

Mark first token

## Signature

```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
def mark_first_token(&mut self) -> ()
```

### Returns

<ResponseField name="Returns" type="()">
  The result of the operation.
</ResponseField>

***

## Related Documentation

<CardGroup cols={2}>
  <Card title="Rust Token Management" icon="coins" href="/docs/rust/token-management" />

  <Card title="Rust Budget" icon="wallet" href="/docs/rust/budget" />
</CardGroup>