Critic Agent
~3 min read
Concept & How It Works
Why Does It Exist?
Generation without critique leads to confident wrong answers. A critic loop catches errors before users see them and provides training signal for improvement.
Real-World Analogy
A critic is a code reviewer on a PR — they don't write the feature but block merge if tests fail or standards aren't met.
Visual Workflows
What is Critic Agent?
Example
Scenario
Writer agent drafts blog post → Critic flags unsupported statistic in paragraph 3 → Writer revises with sourced data.
Solution
In Multi-Agent Systems, apply Critic Agent to this scenario: Writer agent drafts blog post → Critic flags unsupported statistic in paragraph 3 → Writer revises with sourced data. Identify the inputs, run the technique, validate the output, and note one thing you would monitor in production.
Practice Task
Do this before moving to the next module — reading alone is not enough.
Open the Code Walkthrough below and run it locally. Change one parameter related to Critic Agent (e.g. model, temperature, top_k, or tool name), observe the difference in output, and write 2–3 sentences explaining what changed.
Code Walkthrough
Highlighted lines show where Critic Agent happens in the code.
1class Critique(BaseModel): # define a data structure or component2 passed: bool3 issues: list[str]4
5critic = Agent(output_type=Critique, instructions="Score draft against rubric. Be strict on facts.") # key line for Critic Agent6critique = critic.run_sync(f"Task: {task}\nDraft: {draft}").output # key line for Critic Agent7if not critique.passed:8 draft = writer.run_sync(f"Fix: {critique.issues}").outputCommands to Remember
Commands to Remember
pip install langgraph langchain-openai # multi-agent orchestrationpip install crewai # role-based multi-agent crews
Common Mistakes
- Treating Critic Agent as a black box without evaluation
- Ignoring cost and latency in production
- Skipping error handling for critic agent
Cheat Sheet
Quick recap — the most important points from this module.
Cheat Sheet
quick ref- •Critic Agent
- •Rubric
- •Reflexion
- •Critique Loop