Agent skill

behavioral-evals

Guidance for creating, running, fixing, and promoting behavioral evaluations. Use when verifying agent decision logic, debugging failures, debugging prompt steering, or adding workspace regression tests.

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Install this agent skill to your Project

npx add-skill https://github.com/google-gemini/gemini-cli/tree/main/.gemini/skills/behavioral-evals

SKILL.md

Behavioral Evals

Overview

Behavioral evaluations (evals) are tests that validate the agent's decision-making (e.g., tool choice) rather than pure functionality. They are critical for verifying prompt changes, debugging steerability, and preventing regressions.

[!NOTE] Single Source of Truth: For core concepts, policies, running tests, and general best practices, always refer to evals/README.md.


🔄 Workflow Decision Tree

  1. Does a prompt/tool change need validation?
    • No -> Normal integration tests.
    • Yes -> Continue below.
  2. Is it UI/Interaction heavy?
    • Yes -> Use appEvalTest (AppRig). See creating.md.
    • No -> Use evalTest (TestRig). See creating.md.
  3. Is it a new test?
    • Yes -> Set policy to USUALLY_PASSES.
    • No -> ALWAYS_PASSES (locks in regression).
  4. Are you fixing a failure or promoting a test?
    • Fixing -> See fixing.md.
    • Promoting -> See promoting.md.

📋 Quick Checklist

1. Setup Workspace

Seed the workspace with necessary files using the files object to simulate a realistic scenario (e.g., NodeJS project with package.json).

  • Details in creating.md

2. Write Assertions

Audit agent decisions using rig.setBreakpoint() (AppRig only) or index verification on rig.readToolLogs().

  • Details in creating.md

3. Verify

Run single tests locally with Vitest. Confirm stability locally before relying on CI workflows.


📦 Bundled Resources

Detailed procedural guides:

  • creating.md: Assertion strategies, Rig selection, Mock MCPs.
  • fixing.md: Step-by-step automated investigation, architecture diagnosis guidelines.
  • promoting.md: Candidate identification criteria and threshold guidelines.

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