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

# System Message

> Customize the agent's system message and role.

```python system_message.py theme={null}
"""
System Message
=============================

Customize the agent's system message and role.
"""

from agno.agent import Agent
from agno.models.openai import OpenAIResponses

# ---------------------------------------------------------------------------
# Create Agent
# ---------------------------------------------------------------------------
agent = Agent(
    model=OpenAIResponses(id="gpt-5.2"),
    # Override the auto-generated system message with a custom one
    system_message="You are a concise technical writer. Always respond in bullet points. Never use more than 3 sentences per bullet point.",
    # Change the role of the system message (default is "system")
    system_message_role="system",
    markdown=True,
)

# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    agent.print_response(
        "Explain how HTTP cookies work.",
        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 `system_message.py`, then run:

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

Full source: [cookbook/02\_agents/03\_context\_management/system\_message.py](https://github.com/agno-agi/agno/blob/main/cookbook/02_agents/03_context_management/system_message.py)