> ## 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.

# On Span Start • AI Agent SDK

> on_span_start: Called when a span starts.

# on\_span\_start

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

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

Called when a span starts.

## Signature

```python theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}}
def on_span_start(span_id: str, trace_id: str, name: str, parent_span_id: Optional[str], attributes: Optional[Dict[str, Any]]) -> None
```

## Parameters

<ParamField query="span_id" type="str" required={true}>
  No description available.
</ParamField>

<ParamField query="trace_id" type="str" required={true}>
  No description available.
</ParamField>

<ParamField query="name" type="str" required={true}>
  No description available.
</ParamField>

<ParamField query="parent_span_id" type="Optional" required={false}>
  No description available.
</ParamField>

<ParamField query="attributes" type="Optional" required={false}>
  No description available.
</ParamField>

## Source

<Card title="View on GitHub" icon="github" href="https://github.com/MervinPraison/PraisonAI/blob/main/src/praisonai-agents/praisonaiagents/obs/__init__.py#L80">
  `praisonaiagents/obs/__init__.py` at line 80
</Card>