skill-check

name	skill-check
description	ALWAYS use this when the request matches Skill Check: Validate Claude Code skills against the agentskills specification.

SkillCheck

Selective Reading Rule

Start with:

• references/senior-master-standard.md
• references/usage-routing.md
• references/quality-checklist.md

Then load only the inherited docs, scripts, assets, or examples that match the user's actual task.

Overview

Validate SKILL.md files against the agentskills specification and Anthropic best practices. Catches structural errors, semantic contradictions, naming anti-patterns, and quality gaps in a single read-only pass.

When to Use This Skill

• Use when user says "check skill", "skillcheck", or "validate SKILL.md"
• Use when reviewing a skill before publishing to a marketplace
• Use when debugging why a skill doesn't trigger correctly
• Use when onboarding a team to skill authoring standards
• Do NOT use for anti-slop detection, security scanning, or token analysis; use SkillCheck Pro for those

How It Works

Step 1: Parse

Read the target SKILL.md file and extract YAML frontmatter.

Step 2: Validate

Apply all Free tier checks in order:

Category	Checks	What it catches
Structure (1.x)	Name format, description WHAT+WHEN, allowed-tools, categories, XML injection	Malformed frontmatter, missing fields
Body (2.x)	Line count, hardcoded paths, stale dates, empty sections, deprecated syntax, MCP tool qualification	Content quality issues
Naming (3.x)	Vague terms, single-word names, gerund suggestions	Poor discoverability
Semantic (4.x)	Contradictions, ambiguous terms, missing output format, wisdom/platitudes, misplaced triggers	Logical inconsistencies
Quality (8.x)	Examples, error handling, triggers, output format, prerequisites, negative triggers	Strengths (positive patterns)

Step 3: Score

Calculate overall score (0-100). Penalties: critical = -20, warning = -5, suggestion = -1.

Step 4: Report

Return structured results: score, grade (Excellent/Good/Needs Work/Poor), issue list with check IDs, line numbers, messages, and fix suggestions.

Examples

Example 1: Validating a skill

User: check my skill at ~/.claude/skills/weekly-report/SKILL.md

SkillCheck output:
## weekly-report Check Results [FREE]

Score: 85/100 (Good)

### Warnings (2)
  - 1.2-desc-when (line 3): Description missing WHEN clause
  - 4.5-desc-no-triggers (line 3): Description lacks triggering conditions

### Suggestions (1)
  - 3.4-gerund-naming (line 2): Skill name could use gerund form

### Passed Checks: 28

Example 2: Clean skill passes all checks

User: skillcheck ~/.claude/skills/processing-pdfs/SKILL.md

Score: 100/100 (Excellent)
All 31 checks passed. No issues found.

Limitations

• Read-only: does not modify any files
• Free tier covers structural, semantic, and naming checks only
• Anti-slop, security, WCAG, token, enterprise, and workflow checks require SkillCheck Pro
• Semantic checks (contradiction detection, wisdom/platitude) are heuristic with ~5% false positive rate
• Does not validate referenced files or scripts; only checks SKILL.md content
• Single-file validation; does not cross-check against other skills in the same directory

Best Practices

• Run SkillCheck before submitting skills to any marketplace
• Fix all critical and warning issues; suggestions are optional
• Use the check ID (e.g., 1.2-desc-when) to find the exact rule in the skill body
• Re-run after fixes to confirm the score improved

Common Pitfalls

• Problem: Score seems low due to many suggestions Solution: Suggestions cap at -15 points total. Focus on warnings and criticals first.

• Problem: False positive on ambiguous terms inside code blocks Solution: SkillCheck skips code blocks and inline code. If you still see false positives, wrap the term in backticks.

• Problem: Wisdom/platitude check flags legitimate instructions Solution: Rephrase generic advice ("Remember that testing is important") as concrete directives ("Run tests before committing").