> ## Documentation Index
> Fetch the complete documentation index at: https://agno-v2.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

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

**1. Install dependencies**

```bash theme={null}
uv pip install -U agno openai
```

**2. Export your OpenAI API key**

```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"
```

**3. Run the example**

Save the code above as `async_tool_decorator.py`, then run:

```bash theme={null}
python async_tool_decorator.py
```

Full source: [cookbook/91\_tools/tool\_decorator/async\_tool\_decorator.py](https://github.com/agno-agi/agno/blob/v3.0.4/cookbook/91_tools/tool_decorator/async_tool_decorator.py)


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