> ## 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.

# 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

<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 `system_message.py`, then run:

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

Full source: [cookbook/02\_agents/03\_context\_management/system\_message.py](https://github.com/agno-agi/agno/blob/v3.0.4/cookbook/02_agents/03_context_management/system_message.py)


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