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

# Async Tool Decorator

> Define an async generator tool with @tool and stream its yielded results.

```python async_tool_decorator.py theme={null}
"""
Async Tool Decorator
=============================

Demonstrates async tool decorator.
"""

import asyncio
import json
from typing import AsyncIterator

import httpx
from agno.agent import Agent
from agno.tools import tool

# ---------------------------------------------------------------------------
# Create Agent
# ---------------------------------------------------------------------------


@tool(show_result=True)
async def get_top_hackernews_stories(agent: Agent) -> AsyncIterator[str]:
    num_stories = agent.dependencies.get("num_stories", 5) if agent.dependencies else 5

    async with httpx.AsyncClient() as client:
        # Fetch top story IDs
        response = await client.get(
            "https://hacker-news.firebaseio.com/v0/topstories.json"
        )
        story_ids = response.json()

        # Yield story details
        for story_id in story_ids[:num_stories]:
            story_response = await client.get(
                f"https://hacker-news.firebaseio.com/v0/item/{story_id}.json"
            )
            story = story_response.json()
            if "text" in story:
                story.pop("text", None)
            yield json.dumps(story)


agent = Agent(
    dependencies={
        "num_stories": 2,
    },
    tools=[get_top_hackernews_stories],
    markdown=True,
)
# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------

if __name__ == "__main__":
    asyncio.run(
        agent.aprint_response("What are the top hackernews stories?", stream=True)
    )
```

## Run the Example

<Steps>
  <Snippet file="create-venv-step.mdx" />

  <Step title="Install dependencies">
    ```bash theme={null}
    uv pip install -U agno openai
    ```
  </Step>

  <Step title="Export your OpenAI API key">
    <CodeGroup>
      ```bash Mac/Linux theme={null}
      export OPENAI_API_KEY="your_openai_api_key_here"
      ```

      ```bash Windows theme={null}
      $Env:OPENAI_API_KEY="your_openai_api_key_here"
      ```
    </CodeGroup>
  </Step>

  <Step title="Run the example">
    Save the code above as `async_tool_decorator.py`, then run:

    ```bash theme={null}
    python async_tool_decorator.py
    ```
  </Step>
</Steps>

Full source: [cookbook/91\_tools/tool\_decorator/async\_tool\_decorator.py](https://github.com/agno-agi/agno/blob/main/cookbook/91_tools/tool_decorator/async_tool_decorator.py)