> ## Documentation Index
> Fetch the complete documentation index at: https://agno-v2-docs-scavio-google-v2.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom Tool Events

> Yield a custom CustomEvent subclass from an async @tool and consume it while streaming agent.arun().

Yield custom events from a custom tool and consume them while streaming.

```python custom_tool_events.py theme={null}
"""This example demonstrate how to yield custom events from a custom tool."""

import asyncio
from dataclasses import dataclass
from typing import Optional

from agno.agent import Agent
from agno.models.openai import OpenAIChat
from agno.run.agent import CustomEvent
from agno.tools import tool

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


# Our custom event, extending the CustomEvent class
@dataclass
class CustomerProfileEvent(CustomEvent):
    """CustomEvent for customer profile."""

    customer_name: Optional[str] = None
    customer_email: Optional[str] = None
    customer_phone: Optional[str] = None


# Our custom tool
@tool()
async def get_customer_profile():
    """Example custom tool that simply yields a custom event."""

    yield CustomerProfileEvent(
        customer_name="John Doe",
        customer_email="john.doe@example.com",
        customer_phone="1234567890",
    )


# Setup an Agent with our custom tool.
agent = Agent(
    model=OpenAIChat(id="gpt-4o"),
    tools=[get_customer_profile],
    instructions="Your task is to retrieve customer profiles for the user.",
)


async def run_agent():
    # Running the Agent: it should call our custom tool and yield the custom event
    async for event in agent.arun(
        "Hello, can you get me the customer profile for customer with ID 123?",
        stream=True,
    ):
        if isinstance(event, CustomEvent):
            print(f"Custom event emitted: {event}")


# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    asyncio.run(run_agent())
```

## 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 `custom_tool_events.py`, then run:

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

Full source: [cookbook/91\_tools/custom\_tool\_events.py](https://github.com/agno-agi/agno/blob/main/cookbook/91_tools/custom_tool_events.py)