# Source: https://www.traceloop.com/docs/evaluators/guardrails.md

> ## Documentation Index
> Fetch the complete documentation index at: https://www.traceloop.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Guardrails

> Real-time evaluation and safety checks for LLM applications

Guardrails are real-time evaluators that run inline with your application code, providing immediate safety checks, policy enforcement, and quality validation before outputs reach users. Unlike post-hoc evaluation in playgrounds, experiments, or monitors, guardrails execute synchronously during runtime to prevent issues before they occur.

## What Are Guardrails?

Guardrails act as protective middleware layers that intercept and validate LLM inputs and outputs in real-time. They enable you to:

* **Prevent harmful outputs** - Block inappropriate, biased, or unsafe content before it reaches users
* **Enforce business policies** - Ensure responses comply with company guidelines and regulatory requirements
* **Validate quality** - Check for hallucinations, factual accuracy, and relevance in real-time
* **Control behavior** - Enforce tone, style, and format requirements consistently
* **Protect sensitive data** - Detect and prevent leakage of PII, credentials, or confidential information

## How Guardrails Differ from Other Evaluators

| Feature              | Guardrails                  | Experiments          | Monitors                     | Playgrounds           |
| -------------------- | --------------------------- | -------------------- | ---------------------------- | --------------------- |
| **Timing**           | Real-time (inline)          | Post-hoc (batch)     | Post-hoc (continuous)        | Interactive (manual)  |
| **Execution**        | Synchronous with code       | Programmatic via SDK | Automated on production data | User-triggered        |
| **Purpose**          | Prevention & blocking       | Systematic testing   | Quality tracking             | Development & testing |
| **Latency Impact**   | Yes - adds to response time | No                   | No                           | N/A                   |
| **Can Block Output** | Yes                         | No                   | No                           | No                    |

The key distinction is that guardrails run **before** outputs are returned to users, allowing you to intercept and modify or block responses based on evaluation results.

## Use Cases

### Safety and Content Filtering

Prevent toxic, harmful, or inappropriate content from reaching users:

* Detect hate speech, profanity, or offensive language
* Block outputs containing violent or explicit content
* Filter responses that could cause psychological harm

### Regulatory Compliance

Ensure outputs meet legal and regulatory requirements:

* HIPAA compliance for medical information
* GDPR compliance for personal data handling
* Financial services regulations (e.g., avoiding financial advice)
* Industry-specific content guidelines

### Data Protection

Prevent sensitive information leakage:

* Detect PII (personally identifiable information)
* Block API keys, passwords, or credentials in responses
* Prevent disclosure of proprietary business information
* Ensure customer data confidentiality

### Quality Assurance

Maintain output quality standards:

* Detect hallucinations and factual errors
* Verify response relevance to user queries
* Enforce minimum quality thresholds
* Validate structured output formats

### Brand and Tone Control

Ensure consistent brand voice:

* Enforce communication style guidelines
* Maintain appropriate tone for audience
* Prevent off-brand language or messaging
* Control formality levels

## Implementation

### Basic Setup

First, initialize the Traceloop SDK in your application:

```python  theme={null}
from traceloop.sdk import Traceloop

Traceloop.init(app_name="your-app-name")
```

### Using the @guardrail Decorator

Apply the `@guardrail` decorator to functions that interact with LLMs:

```python  theme={null}
from traceloop.sdk.decorators import guardrail
from openai import AsyncOpenAI

client = AsyncOpenAI()

@guardrail(slug="content_safety_check")
async def get_ai_response(user_message: str) -> str:
    response = await client.chat.completions.create(
        model="gpt-4",
        messages=[
            {"role": "system", "content": "You are a helpful assistant."},
            {"role": "user", "content": user_message}
        ],
        temperature=0.7
    )
    return response.choices[0].message.content
```

The `slug` parameter identifies which guardrail evaluator to apply. This corresponds to an evaluator you've defined in the Traceloop dashboard.

### Medical Chat Example

Here's a complete example showing guardrails for a medical chatbot:

```python  theme={null}
import asyncio
import os
from openai import AsyncOpenAI
from traceloop.sdk import Traceloop
from traceloop.sdk.decorators import guardrail

Traceloop.init(app_name="medical-chat-example")

client = AsyncOpenAI(api_key=os.getenv("OPENAI_API_KEY"))

@guardrail(slug="valid_medical_chat")
async def get_doctor_response(conversation_history: list) -> str:
    response = await client.chat.completions.create(
        model="gpt-4o",
        messages=[
            {
                "role": "system",
                "content": """You are a medical information assistant.
                You can provide general health information but you are NOT
                a replacement for professional medical advice.
                Always recommend consulting with qualified healthcare providers
                for specific medical concerns."""
            },
            *conversation_history
        ],
        temperature=0,
        max_tokens=500
    )
    return response.choices[0].message.content

async def medical_chat_session():
    conversation_history = []

    print("Medical Chat Assistant (type 'quit' to exit)")
    print("-" * 50)

    while True:
        user_input = input("\nYou: ").strip()

        if user_input.lower() in ['quit', 'exit', 'q']:
            print("Thank you for using Medical Chat Assistant. Stay healthy!")
            break

        conversation_history.append({"role": "user", "content": user_input})

        try:
            response = await get_doctor_response(conversation_history)
            print(f"\nAssistant: {response}")
            conversation_history.append({"role": "assistant", "content": response})
        except Exception as e:
            print(f"Error: {e}")
            conversation_history.pop()

if __name__ == "__main__":
    asyncio.run(medical_chat_session())
```

### Multiple Guardrails

You can apply multiple guardrails to the same function for layered protection:

```python  theme={null}
@guardrail(slug="content_safety")
@guardrail(slug="pii_detection")
@guardrail(slug="factual_accuracy")
async def generate_response(prompt: str) -> str:
    # Your LLM call here
    pass
```

Guardrails execute in the order they're declared (bottom to top in the decorator stack).

## Creating Guardrail Evaluators

Guardrails use the same evaluator system as experiments and monitors. To create a guardrail evaluator:

1. Navigate to the **Evaluator Library** in your Traceloop dashboard

2. Click **New Evaluator** or select a pre-built evaluator

3. Define your evaluation criteria:
   * For safety checks: Specify content categories to detect and block
   * For compliance: Define regulatory requirements and policies
   * For quality: Set thresholds for relevance, accuracy, or completeness

4. Test the evaluator in a playground to validate behavior

5. Note the evaluator's **slug** for use in your code

6. Apply the evaluator using `@guardrail(slug="your-evaluator-slug")`

See [Custom Evaluators](./custom-evaluator) for detailed instructions on creating evaluators.

## Best Practices

### Performance Considerations

Guardrails add latency to your application since they run synchronously:

* **Use selectively** - Apply guardrails only where needed, not to every function
* **Choose efficient evaluators** - Simpler checks run faster than complex LLM-based evaluations
* **Consider async execution** - Use async/await patterns to maximize throughput
* **Monitor latency** - Track guardrail execution times and optimize slow evaluators
* **Cache when possible** - Cache evaluation results for identical inputs

### Error Handling

Implement robust error handling for guardrail failures:

```python  theme={null}
from traceloop.sdk.decorators import guardrail

@guardrail(slug="safety_check")
async def get_response(prompt: str) -> str:
    try:
        # Your LLM call
        response = await generate_llm_response(prompt)
        return response
    except Exception as e:
        # Log the error
        logger.error(f"Guardrail or LLM error: {e}")
        # Return safe fallback
        return "I apologize, but I cannot process this request at the moment."
```

### Layered Protection

Use multiple layers of guardrails for critical applications:

1. **Input validation** - Check user inputs before processing
2. **Output validation** - Verify LLM responses before returning
3. **Context validation** - Ensure proper use of retrieved information
4. **Post-processing** - Final safety check on formatted outputs

### Testing Guardrails

Before deploying to production:

* **Test in playgrounds** - Validate evaluator behavior with sample inputs
* **Run experiments** - Test guardrails against diverse datasets
* **Monitor false positives** - Track blocked outputs that should have been allowed
* **Monitor false negatives** - Watch for policy violations that weren't caught
* **A/B test** - Compare user experience with and without specific guardrails

### Compliance and Auditing

For regulated industries:

* **Log all evaluations** - Traceloop automatically tracks all guardrail executions
* **Document policies** - Maintain clear documentation of what each guardrail checks
* **Version control** - Track changes to guardrail configurations over time
* **Regular audits** - Review guardrail effectiveness and update as needed
* **Incident response** - Have procedures for when guardrails detect violations

## Configuration Options

When applying guardrails, you can configure behavior:

```python  theme={null}
@guardrail(
    slug="safety_check",
    # Additional configuration options
    blocking=True,        # Whether to block on evaluation failure
    timeout_ms=5000,      # Maximum evaluation time
    fallback="safe"       # Behavior on timeout or error
)
async def get_response(prompt: str) -> str:
    # Your implementation
    pass
```

## Monitoring Guardrail Performance

Track guardrail effectiveness in your Traceloop dashboard:

* **Execution frequency** - How often each guardrail runs
* **Block rate** - Percentage of requests blocked by guardrails
* **Latency impact** - Time added by guardrail evaluation
* **Error rate** - Guardrail failures or timeouts
* **Policy violations** - Trends in detected issues over time

Use this data to optimize guardrail configuration and identify emerging safety concerns.

## Integration with Experiments and Monitors

Guardrails complement other evaluation workflows:

* **Experiments** - Test guardrail effectiveness on historical data before deployment
* **Monitors** - Continuously track guardrail performance in production
* **Playgrounds** - Develop and refine guardrail evaluators interactively

This integrated approach ensures comprehensive quality control across development, testing, and production environments.

## Next Steps

* [Create custom evaluators](./custom-evaluator) for your specific guardrail needs
* [Explore pre-built evaluators](./made-by-traceloop) for common safety and quality checks
* [Set up experiments](../experiments/introduction) to test guardrails before production
* [Configure monitors](../monitoring/introduction) to track guardrail performance over time