/evaluate:skill

Evaluate a skill's effectiveness by running behavioral test cases and grading the results against assertions.

When to Use This Skill

Use this skill when...	Use alternative when...
Want to test if a skill produces correct results	Need structural validation -> scripts/plugin-compliance-check.sh
Validating skill improvements before merging	Want to file feedback about a session -> /feedback:session
Benchmarking a skill against a baseline	Need to check skill freshness -> /health:audit
Creating eval cases for a new skill	Want to review code quality -> /code-review

Context

• Skill file: !find $1/skills -name "SKILL.md" -maxdepth 3
• Eval cases: !find $1/skills -name "evals.json" -maxdepth 3

Parameters

Parse these from $ARGUMENTS:

Parameter	Default	Description
<plugin/skill-name>	required	Path as plugin-name/skill-name
--create-evals	false	Generate eval cases if none exist
--runs N	1	Number of runs per eval case
--baseline	false	Also run without skill for comparison

Execution

Step 1: Resolve skill path

Parse $ARGUMENTS to extract <plugin-name> and <skill-name>. The skill file lives at:

<plugin-name>/skills/<skill-name>/SKILL.md

Read the SKILL.md to confirm it exists and understand what the skill does.

Step 2: Run structural pre-check

Run the compliance check to confirm the skill passes basic structural validation:

bash scripts/plugin-compliance-check.sh <plugin-name>

If structural issues are found, report them and stop. Behavioral evaluation on a structurally broken skill is wasted effort.

Step 3: Load or create eval cases

Look for <plugin-name>/skills/<skill-name>/evals.json.

If the file exists: read and validate it against the evals.json schema (see evaluate-plugin/references/schemas.md).

If the file does not exist AND --create-evals is set: Analyze the SKILL.md and generate eval cases:

1. Read the skill thoroughly — understand its purpose, parameters, execution steps, and expected behaviors.
2. Generate 3-5 eval cases covering:
   • Happy path: Standard usage that should work correctly
   • Edge case: Unusual but valid inputs
   • Boundary: Inputs that test the limits of the skill's scope
3. For each eval case, write:
   • id: Unique identifier (e.g., eval-001)
   • description: What this test validates
   • prompt: The user prompt to simulate
   • expectations: List of assertion strings the output should satisfy
   • tags: Categorization tags
4. Write the generated cases to <plugin-name>/skills/<skill-name>/evals.json.

If the file does not exist AND --create-evals is NOT set: Report that no eval cases exist and suggest running with --create-evals.

Step 4: Run evaluations

For each eval case, for each run (up to --runs N):

1. Create a results directory: <plugin-name>/skills/<skill-name>/eval-results/runs/<eval-id>-run-<N>/
2. Record the start time.
3. Spawn a Task subagent (subagent_type: general-purpose) that:
   • Receives the skill content as context
   • Executes the eval prompt
   • Works in the repository as if it were a real user request
4. Capture the subagent output.
5. Record timing data (duration) and write to timing.json.
6. Write the transcript to transcript.md.

Step 5: Run baseline (if --baseline)

If --baseline is set, repeat Step 4 but without loading the skill content. This creates a comparison point to measure skill effectiveness.

Use the same eval prompts and record results in a parallel baseline/ subdirectory.

Step 6: Grade results

For each run, delegate grading to the eval-grader agent via Task:

Task subagent_type: eval-grader
Prompt: Grade this eval run against the assertions.
  Eval case: <eval case from evals.json>
  Transcript: <path to transcript.md>
  Output artifacts: <list of created/modified files>

The grader produces grading.json for each run.

Step 7: Aggregate and report

Compute aggregate statistics across all runs:

• Mean pass rate (assertions passed / total assertions)
• Standard deviation of pass rate
• Mean duration

If --baseline was used, also compute:

• Baseline mean pass rate
• Delta (improvement from skill)

Write aggregated results to <plugin-name>/skills/<skill-name>/eval-results/benchmark.json.

Print a summary table:

## Evaluation Results: <plugin/skill-name>

| Metric | With Skill | Baseline | Delta |
|--------|-----------|----------|-------|
| Pass Rate | 85% | 42% | +43% |
| Duration | 14s | 12s | +2s |
| Runs | 3 | 3 | — |

### Per-Eval Breakdown

| Eval | Description | Pass Rate | Status |
|------|-------------|-----------|--------|
| eval-001 | Basic usage | 100% | PASS |
| eval-002 | Edge case | 67% | PARTIAL |
| eval-003 | Boundary | 100% | PASS |

Agentic Optimizations

Context	Command
Check skill exists	ls <plugin>/skills/<skill>/SKILL.md
Check evals exist	ls <plugin>/skills/<skill>/evals.json
Read evals	cat <plugin>/skills/<skill>/evals.json | jq .
Create results dir	mkdir -p <plugin>/skills/<skill>/eval-results/runs
Write JSON	jq -n '<expression>' > file.json
Aggregate results	bash evaluate-plugin/scripts/aggregate_benchmark.sh <plugin>

Quick Reference

Flag	Description
--create-evals	Generate eval cases from SKILL.md analysis
--runs N	Number of runs per eval case (default: 1)
--baseline	Run without skill for comparison