# More factual responses
response = completion(
    model="xai/grok-beta",
    messages=[{"role": "user", "content": "Explain quantum computing"}],
    temperature=0.1,
    max_tokens=500
)
```

### System Messages for Behavior Control

Use system messages to guide Grok's behavior:

```python
response = completion(
    model="xai/grok-beta",
    messages=[
        {"role": "system", "content": "You are a helpful scientific advisor. Provide accurate, evidence-based information."},
        {"role": "user", "content": "What are the current challenges in fusion energy research?"}
    ]
)
```

## Feedback Scores and Evaluation

Once your xAI calls are logged with Opik, you can evaluate your LLM application using Opik's evaluation framework:

```python
from opik.evaluation import evaluate
from opik.evaluation.metrics import Hallucination