Lesson 968 of 2116
Agent Evaluation Harnesses: Beyond Unit Tests for Multi-Step Behaviors
Agent behaviors emerge from multi-step interactions; unit tests on individual tools miss the failures that matter. Real evaluation requires task-completion harnesses with tracing and human review.
Lesson map
What this lesson covers
Learning path
The main moves in order
- 1The premise
- 2agent evaluation
- 3task completion
- 4tracing
Concept cluster
Terms to connect while reading
Section 1
The premise
Agent quality emerges across trajectories, not within individual steps; evaluation must span trajectories.
What AI does well here
- Build task-completion harnesses with realistic input distribution and ground-truth outcomes
- Implement tracing that captures the full trajectory (prompts, tool calls, tool outputs, model decisions)
- Use trajectory analysis to identify common failure modes (loops, premature stopping, wrong tool selection)
- Maintain regression test suites that catch behavior degradation across model updates
What AI cannot do
- Substitute for human review on high-stakes trajectories
- Catch novel failure modes the test set doesn't cover
- Replace production monitoring (eval-set performance ≠ production performance)
Key terms in this lesson
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