eval-harness

Implements eval-driven development with capability evals, regression evals, and pass@k metrics for AI coding sessions.

2|Updated Feb 25, 2026
One-click install
npx skills add https://github.com/adamreger/ecc-antigravity --skill eval-harness-adamreger
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: eval-harness
Source: https://github.com/adamreger/ecc-antigravity/tree/main/skills/eval-harness
Command: npx skills add https://github.com/adamreger/ecc-antigravity --skill eval-harness-adamreger

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? AI-assisted coding lacks a systematic way to verify that agent outputs actually meet requirements and that new changes do not break existing behavior. This Skill provides a formal evaluation framework that treats evals as the unit tests of AI development, letting you define pass/fail criteria before implementation and measure agent reliability over time. ## Core Features & Use Cases - Capability and Regression Evals: Define structured eval templates that test whether Claude can accomplish new tasks and whether existing functionality still works after changes. - Multiple Grader Types: Use deterministic code-based graders (grep checks, test runs, build verification), model-based graders for open-ended outputs, or human review flags for high-risk changes. - Reliability Metrics: Track pass@k (at least one success in k attempts) and pass^k (all k trials succeed) to quantify agent reliability across model versions and prompt changes. - Use Case: Before adding authentication to your app, define capability evals (user registration, login, session persistence) and regression evals (public routes still work), implement the feature, then run the evals and generate a report showing pass@3 of 100% before shipping. ## Quick Start Ask the AI to define an eval-driven development plan with capability and regression evals for the feature you are about to build.

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, listing concrete pass/fail criteria for the feature. Then implement the code, run the evals using code-based graders like test commands or grep checks, and generate a report tracking pass@k metrics.

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

pass@k measures whether at least one of k attempts succeeds, with pass@3 above 90% as a typical target. pass^k requires all k trials to succeed consecutively, making it a stricter bar suited for critical paths and regression evals.

How do I create regression tests for AI agent changes?▼

Create a regression eval that records a baseline SHA or checkpoint, then lists existing functionality tests with PASS/FAIL results. Run these evals after every prompt, model, or code change to confirm previously working behavior remains intact.

When should I use a model-based grader instead of a code-based grader?▼

Use code-based graders for deterministic checks like test passes, build success, or pattern matching, since they are reproducible. Use model-based graders only for open-ended outputs like code quality or structure, and human review for security-sensitive changes.

Where should eval definitions be stored in a project?▼

Store evals as versioned files in a dedicated directory such as .claude/evals/, with one markdown file per feature plus run logs and a baseline.json for regression checkpoints. Evals are first-class artifacts and should be committed alongside the code they verify.