> ## 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.

# Cerebras Default COT Fallback

> Stream a Cerebras agent's default chain-of-thought with reasoning and debug mode enabled.

Demonstrates default chain-of-thought behavior with a Cerebras model.

<Warning>
  This example uses a Cerebras model ID that has been retired. Replace the retired ID with `gpt-oss-120b` before running. Review the [Cerebras migration notes](https://inference-docs.cerebras.ai/support/deprecation) when the example uses reasoning, tools, or structured output.
</Warning>

```python cerebras_llama_default_COT.py theme={null}
"""
Cerebras Default COT Fallback
=============================

Demonstrates default chain-of-thought behavior with a Cerebras model.
"""

from agno.agent import Agent
from agno.models.cerebras import Cerebras

# ---------------------------------------------------------------------------
# Create Agent
# ---------------------------------------------------------------------------
reasoning_agent = Agent(
    model=Cerebras(id="llama-3.3-70b"),
    reasoning=True,
    debug_mode=True,
    markdown=True,
)

# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    reasoning_agent.print_response(
        "Give me steps to write a python script for fibonacci series",
        stream=True,
        show_full_reasoning=True,
    )
```

## Run the Example

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

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

  <Step title="Export your Cerebras API key">
    <CodeGroup>
      ```bash Mac/Linux theme={null}
      export CEREBRAS_API_KEY="your_cerebras_api_key_here"
      ```

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

  <Step title="Use a current Cerebras model">
    Replace `llama-3.3-70b` with `gpt-oss-120b` in the saved Python file before running.
  </Step>

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

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

Full source: [cookbook/10\_reasoning/agents/cerebras\_llama\_default\_COT.py](https://github.com/agno-agi/agno/blob/main/cookbook/10_reasoning/agents/cerebras_llama_default_COT.py)