
Behavioral Evaluations
OfficialFreeValidate agent decision-making with structured tests.
Free Β· Opens the source repo
What Behavioral Evaluations does
Behavioral evaluations provide a framework for testing and validating the decision-making processes of AI agents. Unlike standard functionality tests, these evaluations focus on how agents choose tools and make decisions based on prompts. This is crucial for ensuring that modifications to prompts or tools do not inadvertently degrade performance or lead to unexpected behaviors. The skill offers a structured approach to creating, running, fixing, and promoting these evaluations, making it an essential tool for developers working with AI agents.
The workflow begins with determining whether a prompt or tool change requires validation. If so, the next steps involve selecting the appropriate evaluation method based on the nature of the interactionβwhether it is UI-heavy or not. The skill provides clear guidance on setting up tests, including how to seed workspaces with realistic scenarios and write assertions that effectively audit agent decisions. This ensures that the evaluations are thorough and accurately reflect the agent's capabilities.
In addition to creating new tests, the skill also addresses how to fix failures and promote tests that have been validated. This is particularly useful for maintaining the integrity of the agent's decision-making logic over time. With bundled resources like procedural guides for creating, fixing, and promoting evaluations, users have access to comprehensive documentation that supports them at every stage of the evaluation process.
Overall, Behavioral Evaluations is designed for developers and teams who need to ensure the reliability and correctness of AI agent behaviors. By implementing these structured tests, they can confidently deploy updates and modifications while minimizing the risk of regressions or failures in decision-making.
When to use it
Use this skill when you need to validate changes to prompts or tools that affect agent decision-making, particularly in complex interactions.
When not to use it
This skill is not suitable for general functionality testing outside of decision-making contexts or for agents that do not require behavioral validation.
What you can build with it
Validating Prompt Changes
When modifying prompts for an AI agent, use behavioral evaluations to ensure that the changes do not negatively impact decision-making.
Debugging Agent Failures
If an AI agent exhibits unexpected behavior, behavioral evaluations can help identify issues in decision logic and provide a structured approach to debugging.
Promoting New Tests
After creating new evaluations, use the skill to promote them effectively, ensuring that they meet the necessary criteria for reliability.
How to install Behavioral Evaluations
View source1. Install with the skills CLI
npx skills add google-gemini/gemini-cli/behavioral-evals --agent claude-code2. Or install it manually
Download the skill folder and drop it into ~/.claude/skills/ for all projects, or .claude/skills/ to scope it to one repo. Restart Claude Code so it picks up the new skill.
Anthropic's agentic coding CLI, and the reference implementation of Agent Skills. Drop a skill folder into ~/.claude/skills and Claude Code loads it automatically whenever a task matches the skill's description. Claude Code docs
Inside SKILL.md
Written by google-geminiBehavioral 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.
π Workflow Decision Tree
- Does a prompt/tool change need validation?
- No -> Normal integration tests.
- Yes -> Continue below.
- Is it UI/Interaction heavy?
- Yes -> Use
appEvalTest(AppRig). See creating.md. - No -> Use
evalTest(TestRig). See creating.md.
- Yes -> Use
- Is it a new test?
- Yes -> Set policy to
USUALLY_PASSES. - No ->
ALWAYS_PASSES(locks in regression).
- Yes -> Set policy to
- Are you fixing a failure or promoting a test?
- Fixing -> See fixing.md.
- Promoting -> See promoting.md.
π 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.
- See evals/README.md for running commands.
π¦ 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.
Frequently asked questions about Behavioral Evaluations
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