Eval Harness

# Eval Harness Skill

A formal evaluation framework for Claude Code sessions, implementing eval-driven development (EDD) principles.

## When to Activate

- Setting up eval-driven development (EDD) for AI-assisted workflows
- Defining pass/fail criteria for Claude Code task completion
- Measuring agent reliability with pass@k metrics
- Creating regression test suites for prompt or agent changes
- Benchmarking agent performance across model versions

## Philosophy

Eval-Driven Development treats evals as the "unit tests of AI development":
- Define expected behavior BEFORE implementation
- Run evals continuously during development
- Track regressions with each change
- Use pass@k metrics for reliability measurement

## Eval Types

### Capability Evals
Test if Claude can do something it couldn't before:
```markdown
[CAPABILITY EVAL: feature-name]
Task: Description of what Claude should accomplish
Success Criteria:
  - [ ] Criterion 1
  - [ ] Criterion 2
  - [ ] Criterion 3
Expected Output: Description of expected result
```

### Regression Evals
Ensure changes don't break existing functionality:
```markdown
[REGRESSION EVAL: feature-name]
Baseline: SHA or checkpoint name
Tests:
  - existing-test-1: PASS/FAIL
  - existing-test-2: PASS/FAIL
  - existing-test-3: PASS/FAIL
Result: X/Y passed (previously Y/Y)
```

## Grader Types

### 1. Code-Based Grader
Deterministic checks using code: