Guardrails are built-in safeguards for your Teams. You can use them to make sure the input you send to the LLM is safe and doesn’t contain anything undesired. Some of the most popular usages are:
  • PII detection and redaction
  • Prompt injection defense
  • Jailbreak defense
  • Data leakage prevention
  • NSFW content filtering

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Agno built-in Guardrails

To simplify the usage of guardrails, Agno provides some built-in guardrails you can use out of the box:
  • PIIDetectionGuardrail: detect PII (Personally Identifiable Information). See the PII Detection Guardrail for agents page for more information.
  • PromptInjectionGuardrail: detect and stop prompt injection attemps. See the Prompt Injection Guardrail for agents page for more information.
  • OpenAIModerationGuardrail: detect content that violates OpenAI’s content policy. See the OpenAI Moderation Guardrail for agents page for more information.
To use the Agno built-in guardrails, you just need to import them and pass them to the Team with the pre_hooks parameter: 
from agno.guardrails import PIIDetectionGuardrail
from agno.team import Team
from agno.models.openai import OpenAIChat

pii_guardrail = PIIDetectionGuardrail()

team = Team(
    name="Privacy-Protected Team",
    model=OpenAIChat(id="gpt-5-mini"),
    pre_hooks=[pii_guardrail],
)
You can some complete examples using the Agno Guardrails in the examples section.

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Custom Guardrails

You can create custom guardrails by extending the BaseGuardrail class. This is useful if you need to perform any check or transformation not handled by the built-in guardrails, or just to implement your own validation logic. You will need to implement the check and async_check methods to perform your validation and raise exceptions when detecting undesired content.
Agno automatically uses the sync or async version of the guardrail based on whether you are running the team with .run() or .arun().
For example, let’s create a simple custom guardrail that checks if the input contains any URLs: 
import re

from agno.exceptions import CheckTrigger, InputCheckError
from agno.guardrails import BaseGuardrail
from agno.run.team import TeamRunInput


class URLGuardrail(BaseGuardrail):
    """Guardrail to identify and stop inputs containing URLs."""

    def check(self, run_input: TeamRunInput) -> None:
        """Raise InputCheckError if the input contains any URLs."""
        if isinstance(run_input.input_content, str):
            # Basic URL pattern
            url_pattern = r'https?://[^\s]+|www\.[^\s]+|[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}[^\s]*'
            if re.search(url_pattern, run_input.input_content):
                raise InputCheckError(
                    "The input seems to contain URLs, which are not allowed.",
                    check_trigger=CheckTrigger.INPUT_NOT_ALLOWED,
                )

    async def async_check(self, run_input: TeamRunInput) -> None:
        """Raise InputCheckError if the input contains any URLs."""
        if isinstance(run_input.input_content, str):
            # Basic URL pattern
            url_pattern = r'https?://[^\s]+|www\.[^\s]+|[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}[^\s]*'
            if re.search(url_pattern, run_input.input_content):
                raise InputCheckError(
                    "The input seems to contain URLs, which are not allowed.",
                    check_trigger=CheckTrigger.INPUT_NOT_ALLOWED,
                )
Now you can use your custom guardrail in your Team: 
from agno.team import Team
from agno.models.openai import OpenAIChat

# Team using our URLGuardrail
team = Team(
    name="URL-Protected Team",
    model=OpenAIChat(id="gpt-5-mini"),
    # Provide the Guardrails to be used with the pre_hooks parameter
    pre_hooks=[URLGuardrail()],
)

# This will raise an InputCheckError
team.run("Can you check what's in https://fake.com?")

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