skill-lab 0.4.0

A Python CLI tool for evaluating agent skills through static analysis, trigger testing, and trace analysis

Skill Lab

A Python CLI tool for evaluating agent skills through static analysis, trigger testing, and trace analysis.

Features

• SKILL.md Parsing: Parse YAML frontmatter and markdown body from skill definitions
• 19 Static Checks: Comprehensive checks across 4 dimensions
  • Structure: File existence, folder organization, frontmatter validation, standard fields
  • Naming: Format, directory matching
  • Description: Required, non-empty, max length
  • Content: Examples, line budget, reference depth
• Trigger Testing: Test skill activation with 4 trigger types (explicit, implicit, contextual, negative)
• Trigger Generation: LLM-powered test case generation via Anthropic API
• Skill Inspector: sklab info shows metadata and token cost estimates
• Prompt Export: sklab prompt exports skills as XML, Markdown, or JSON for agent platforms
• Quality Scoring: Weighted 0-100 score based on check results
• Multiple Output Formats: Console (rich formatting) and JSON

Installation

# From PyPI
pip install skill-lab

# With LLM-based trigger generation (requires Anthropic API)
pip install skill-lab[generate]

# From source
pip install -e .

# With development dependencies
pip install -e ".[dev]"

Setup

API Key (required for sklab generate)

sklab generate uses the Anthropic API to generate trigger test cases. Set your API key:

export ANTHROPIC_API_KEY=sk-ant-...

Get your key at console.anthropic.com.

Model Configuration (optional)

The default model is claude-haiku-4-5-20251001. Override it per-command or globally:

# Per-command
sklab generate ./my-skill --model claude-sonnet-4-5-20250929

# Global default via environment variable
export SKLAB_MODEL=claude-sonnet-4-5-20250929

Quick Start

# Evaluate a skill (path defaults to current directory)
sklab evaluate ./my-skill
sklab evaluate                    # Uses current directory

# Quick validation (pass/fail)
sklab validate ./my-skill

# Inspect skill metadata and token costs
sklab info ./my-skill
sklab info ./my-skill --json      # Machine-readable output

# Export skills as a prompt for agent platforms
sklab prompt ./skill-a ./skill-b  # XML (default)
sklab prompt -f markdown          # Markdown format
sklab prompt -f json              # JSON format

# Generate trigger test cases (requires ANTHROPIC_API_KEY)
sklab generate ./my-skill

# Run trigger tests
sklab trigger ./my-skill

# List available checks
sklab list-checks

Usage

Evaluate a Skill

# Console output (default)
sklab evaluate ./my-skill

# JSON output
sklab evaluate ./my-skill --format json

# Save to file
sklab evaluate ./my-skill --output report.json

# Verbose (show all checks, not just failures)
sklab evaluate ./my-skill --verbose

# Spec-only (skip quality suggestions)
sklab evaluate ./my-skill --spec-only

Quick Validation

# Returns exit code 0 if valid, 1 if invalid
sklab validate ./my-skill

List Available Checks

# List all checks
sklab list-checks

# Filter by dimension
sklab list-checks --dimension structure

# Show only spec-required checks
sklab list-checks --spec-only

Inspect Skill Metadata

View skill metadata and token cost estimates:

# Rich-formatted panel (default)
sklab info ./my-skill

# JSON output (pipe-friendly)
sklab info ./my-skill --json

# Extract a single field
sklab info ./my-skill --field name
sklab info ./my-skill --field tokens

Token estimates show discovery cost (name + description, what agents see when choosing skills) and activation cost (full SKILL.md, loaded when the skill is invoked).

Export as Prompt

Export one or more skills into a prompt format for agent platforms:

# XML format (default, recommended for Claude)
sklab prompt ./skill-a ./skill-b

# Markdown format
sklab prompt ./my-skill -f markdown

# JSON format
sklab prompt ./my-skill -f json

Output goes to stdout for easy piping. A token estimate summary is printed to stderr.

Generate Trigger Tests

Auto-generate trigger test cases from a SKILL.md using an LLM:

# Generate tests (writes to .skill-lab/tests/triggers.yaml)
sklab generate ./my-skill

# Use a specific model
sklab generate ./my-skill --model claude-sonnet-4-5-20250929

# Overwrite existing tests
sklab generate ./my-skill --force

Generates ~13 test cases across 4 trigger types:

• explicit (3): Direct $skill-name invocation
• implicit (3): Describes the need without naming the skill
• contextual (3): Realistic prompts with project context
• negative (4): Adjacent requests that should NOT trigger

Token usage and cost are displayed after each run.

Trigger Testing

Run the generated (or hand-written) trigger tests against a real LLM:

# Run trigger tests (path defaults to current directory)
sklab trigger ./my-skill
sklab trigger                     # Uses current directory

# Filter by trigger type
sklab trigger --type explicit
sklab trigger --type negative

Prerequisites: Trigger testing requires:

• Claude CLI: Install via npm install -g @anthropic-ai/claude-code

Test Definition (.skill-lab/tests/triggers.yaml):

skill: my-skill
test_cases:
  - id: explicit-1
    name: "Direct invocation to do something"
    type: explicit
    prompt: "$my-skill do something"
    expected: trigger
  - id: negative-1
    name: "Unrelated question (should not trigger)"
    type: negative
    prompt: "unrelated question"
    expected: no_trigger

Output Format (JSON)

{
  "skill_path": "/path/to/skill",
  "skill_name": "my-skill",
  "timestamp": "2026-01-25T14:30:00Z",
  "duration_ms": 45.3,
  "quality_score": 87.5,
  "overall_pass": true,
  "checks_run": 19,
  "checks_passed": 17,
  "checks_failed": 2,
  "results": [...],
  "summary": {
    "by_severity": {...},
    "by_dimension": {...}
  }
}

Development

# Install dev dependencies
pip install -e ".[dev]"

# Run tests
pytest tests/ -v

# Run with coverage
pytest tests/ --cov=skill_lab

# Type checking
mypy src/

# Linting
ruff check src/

# Format code
ruff format src/

License

MIT