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"""
Post Hook Output
=============================
Example demonstrating output validation using post-hooks with Agno Agent.
"""
import asyncio
from agno.agent import Agent
from agno.exceptions import CheckTrigger, OutputCheckError
from agno.models.openai import OpenAIResponses
from agno.run.agent import RunOutput
from pydantic import BaseModel
# ---------------------------------------------------------------------------
# Create Agent
# ---------------------------------------------------------------------------
class OutputValidationResult(BaseModel):
is_complete: bool
is_professional: bool
is_safe: bool
concerns: list[str]
confidence_score: float
def validate_response_quality(run_output: RunOutput) -> None:
"""
Post-hook: Validate the agent's response for quality and safety.
This hook checks:
- Response completeness (not too short or vague)
- Professional tone and language
- Safety and appropriateness of content
Raises OutputCheckError if validation fails.
"""
# Skip validation for empty responses
if not run_output.content or len(run_output.content.strip()) < 10:
raise OutputCheckError(
"Response is too short or empty",
check_trigger=CheckTrigger.OUTPUT_NOT_ALLOWED,
)
# Create a validation agent
validator_agent = Agent(
name="Output Validator",
model=OpenAIResponses(id="gpt-5-mini"),
instructions=[
"You are an output quality validator. Analyze responses for:",
"1. COMPLETENESS: Response addresses the question thoroughly",
"2. PROFESSIONALISM: Language is professional and appropriate",
"3. SAFETY: Content is safe and doesn't contain harmful advice",
"",
"Provide a confidence score (0.0-1.0) for overall quality.",
"List any specific concerns found.",
"",
"Be reasonable - don't reject good responses for minor issues.",
],
output_schema=OutputValidationResult,
)
validation_result = validator_agent.run(
input=f"Validate this response: '{run_output.content}'"
)
result = validation_result.content
# Check validation results and raise errors for failures
if not result.is_complete:
raise OutputCheckError(
f"Response is incomplete. Concerns: {', '.join(result.concerns)}",
check_trigger=CheckTrigger.OUTPUT_NOT_ALLOWED,
)
if not result.is_professional:
raise OutputCheckError(
f"Response lacks professional tone. Concerns: {', '.join(result.concerns)}",
check_trigger=CheckTrigger.OUTPUT_NOT_ALLOWED,
)
if not result.is_safe:
raise OutputCheckError(
f"Response contains potentially unsafe content. Concerns: {', '.join(result.concerns)}",
check_trigger=CheckTrigger.OUTPUT_NOT_ALLOWED,
)
if result.confidence_score < 0.6:
raise OutputCheckError(
f"Response quality score too low ({result.confidence_score:.2f}). Concerns: {', '.join(result.concerns)}",
check_trigger=CheckTrigger.OUTPUT_NOT_ALLOWED,
)
def simple_length_validation(run_output: RunOutput) -> None:
"""
Simple post-hook: Basic validation for response length.
Ensures responses are neither too short nor excessively long.
"""
content = run_output.content.strip()
if len(content) < 20:
raise OutputCheckError(
"Response is too brief to be helpful",
check_trigger=CheckTrigger.OUTPUT_NOT_ALLOWED,
)
if len(content) > 5000:
raise OutputCheckError(
"Response is too lengthy and may overwhelm the user",
check_trigger=CheckTrigger.OUTPUT_NOT_ALLOWED,
)
async def main():
"""Demonstrate output validation post-hooks."""
print("Output Validation Post-Hook Example")
print("=" * 60)
# Agent with comprehensive output validation
agent_with_validation = Agent(
name="Customer Support Agent",
model=OpenAIResponses(id="gpt-5-mini"),
post_hooks=[validate_response_quality],
instructions=[
"You are a helpful customer support agent.",
"Provide clear, professional responses to customer inquiries.",
"Be concise but thorough in your explanations.",
],
)
# Agent with simple validation only
agent_simple = Agent(
name="Simple Agent",
model=OpenAIResponses(id="gpt-5-mini"),
post_hooks=[simple_length_validation],
instructions=[
"You are a helpful assistant. Keep responses focused and appropriate length."
],
)
# Test 1: Good response (should pass validation)
print("\n[TEST 1] Well-formed response")
print("-" * 40)
try:
await agent_with_validation.aprint_response(
input="How do I reset my password on my Microsoft account?"
)
print("[OK] Response passed validation")
except OutputCheckError as e:
print(f"[ERROR] Validation failed: {e}")
print(f" Trigger: {e.check_trigger}")
# Test 2: Force a short response (should fail simple validation)
print("\n[TEST 2] Too brief response")
print("-" * 40)
try:
# Use a more constrained instruction to get a brief response
brief_agent = Agent(
name="Brief Agent",
model=OpenAIResponses(id="gpt-5-mini"),
post_hooks=[simple_length_validation],
instructions=["Answer in 1-2 words only."],
)
await brief_agent.aprint_response(input="What is the capital of France?")
except OutputCheckError as e:
print(f"[ERROR] Validation failed: {e}")
print(f" Trigger: {e.check_trigger}")
# Test 3: Normal response with simple validation
print("\n[TEST 3] Normal response with simple validation")
print("-" * 40)
try:
await agent_simple.aprint_response(
input="Explain what a database is in simple terms."
)
print("[OK] Response passed simple validation")
except OutputCheckError as e:
print(f"[ERROR] Validation failed: {e}")
print(f" Trigger: {e.check_trigger}")
# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------
if __name__ == "__main__":
asyncio.run(main())
Run the Example
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Ask AI
# Clone and setup repo
git clone https://github.com/agno-agi/agno.git
cd agno/cookbook/02_agents/09_hooks
# Create and activate virtual environment
./scripts/demo_setup.sh
source .venvs/demo/bin/activate
python post_hook_output.py