eval-harness

Implements eval-driven development with pass/fail criteria and pass@k metrics for Claude Code sessions.

Updated Apr 18, 2026
One-click install
npx skills add https://github.com/JohnRebellion/.claude-public --skill eval-harness-johnrebellion
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: eval-harness
Source: https://github.com/JohnRebellion/.claude-public/tree/main/claude/skills/eval-harness
Command: npx skills add https://github.com/JohnRebellion/.claude-public --skill eval-harness-johnrebellion

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? AI-assisted coding lacks objective quality gates, making it hard to know whether an agent's output actually works or whether a prompt change broke existing behavior. This Skill provides a formal evaluation framework that treats evals as unit tests for AI development. ## Core Features & Use Cases - Capability and Regression Evals: Define pass/fail criteria before implementation and verify that changes do not break existing functionality. - Multiple Grader Types: Use deterministic code graders, model-based LLM-as-judge graders, or human review flags depending on the output type. - Reliability Metrics: Track pass@k and pass^k metrics to measure agent reliability across attempts and model versions. - Use Case: Before adding an authentication feature, define capability evals (user registration, login, session persistence) and regression evals (existing routes unchanged), then run evals after implementation and generate a report showing pass@3 of 100% before shipping. ## Quick Start Ask the agent to define an eval for a new feature with pass/fail criteria, then implement the feature and run the evals to generate a pass/fail report.

Frequently Asked Questions about eval-harness

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I set up eval-driven development for AI coding agents?▼

Define capability and regression evals before writing any code, specifying concrete pass/fail criteria for each behavior. After implementation, run the evals and generate a report tracking pass@k metrics to decide whether the change is ready to ship.

What is the difference between pass@k and pass^k metrics?▼

pass@k measures whether at least one of k attempts succeeds, indicating practical reliability under retries. pass^k requires all k attempts to succeed, making it a stricter stability test recommended for release-critical regression paths.

When should I use a code grader versus a model grader?▼

Use code graders for deterministic checks like grep patterns, test suites, and build success since they are reproducible. Use model graders for open-ended outputs where quality judgment is needed, and human graders for security-sensitive or ambiguous changes.

How do I create regression evals for prompt or agent changes?▼

Record a baseline SHA or checkpoint, list the existing behaviors that must keep passing, and re-run them after each change. The eval report compares current results against the baseline to catch regressions early.

What are common eval anti-patterns to avoid?▼

Avoid overfitting prompts to known eval examples, measuring only happy-path outputs, ignoring cost and latency drift, and allowing flaky graders in release gates. Keep evals fast and version them alongside the code they test.