Demystifying evals for AI agents
The clearest official explanation of what an agent eval actually is.
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How do I test an AI agent and know when it's reliable enough to trust?
The short answer
You test agents with evals: a set of real tasks plus grading logic, run repeatedly because the same input can produce different outputs. Start embarrassingly simple: read 50 transcripts of your agent working, label every failure, turn the recurring ones into automated checks (code checks where possible, an LLM judge validated against your own labels where judgment is needed). Trust is earned per task: track pass rates over many runs, not one good demo.
A quick orientation. The real value is below: resources worth your time, from people who've actually done it.
18 resources worth your time
LLM Evals: Everything You Need to Know (FAQ)
Every question you will have about evals, answered by the field's top teacher.
Open hamel.dev →AI Evals For Engineers & Product Managers
The philosophy behind the top-grossing evals course, free to read.
Open hamelhusain.substack.com →AI Evals For Engineers & PMs (Maven course)
The course that trained 2,000+ people, including teams at OpenAI and Anthropic.
Open maven.com →
Why AI evals are the hottest new skill for product builders
A live walkthrough of building an eval from real product data.
Watch on YouTube youtube.com →Why AI evals are the hottest new skill (audio)
The same masterclass in podcast form for the commute.
Listen on Spotify open.spotify.com →Lenny on evals: watch them build one live
The 60-second version of why evals became the must-have skill.
Open x.com →AI Evals Step-by-Step: Hamel & Shreya Masterclass
Written notes of the full workflow: error analysis to automated judges.
Open aakashg.com →Agent Evaluation: A Detailed Guide
Explains pass@k and why you must run agent tests many times.
Open cameronrwolfe.substack.com →10 Things I Hate About AI Evals
The honest failure modes of eval culture, so you avoid cargo-culting it.
Open vanishinggradients.fireside.fm →Evaluating AI Agents in Practice: Benchmarks, Frameworks, and Lessons Learned
Field lessons from teams that moved agents from demo to production.
Open infoq.com →AI Agent Evaluation: A Practical Step-by-Step Guide
A single-sitting starter recipe for your first agent eval.
Open zenvanriel.com →Evaluating AI Agents: A Practical Guide
Covers the metrics that matter: task success, step count, faithfulness.
Open turingcollege.com →Building eval systems that improve your AI product
Connects evals to shipping cadence rather than treating them as QA theatre.
Open lennysnewsletter.com →AI Evals Course Homework: the Recipe Bot Workflow
A worked example you can copy line by line for your own product.
Open arize.com →How to Do AI Evals Step-by-Step with Real Production Data
A second full session using messy real data instead of toy examples.
Open news.aakashg.com →AI Agent Evaluation: Frameworks, Strategies, and Best Practices
Surveys the tooling landscape so you do not build eval infrastructure from scratch.
Open medium.com →10 Essential Steps for Evaluating the Reliability of AI Agents
A checklist to run before you let an agent near customers.
Open getmaxim.ai →More in AI Agents
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