Skill Check

Validate and review skills against the Agent Skills specification. Combines validation (catch errors) and review (suggest improvements) in one pass.

Quick Start

1. Locate the skill to check
2. Run validation checks (syntax, structure, requirements)
3. Run review checks (discoverability, clarity, conciseness)
4. Report findings with specific fixes
5. Optionally apply improvements

Instructions

Step 1: Locate and Read the Skill

# Personal skills
~/.claude/skills/[skill-name]/SKILL.md

# Project skills
.claude/skills/[skill-name]/SKILL.md

Use Read to examine:

• SKILL.md content (especially YAML frontmatter)
• Supporting files (if any)
• Directory structure

Step 2: Create Validation Checklist

Use TodoWrite to track validation and review items. This ensures thorough coverage and shows progress.

Step 3: Run Validation Checks

A. YAML Frontmatter

Required Fields:

• name present and non-empty
• description present and non-empty

Syntax:

• Opens with --- on line 1
• Closes with --- before Markdown content
• Uses spaces (not tabs) for indentation
• Special characters quoted if needed

Optional Fields (if present):

• allowed-tools uses space-delimited tool names
• license, compatibility, metadata properly formatted

B. Naming Conventions

• Lowercase letters, numbers, hyphens only
• 1-64 characters
• Must match parent directory name
• No -- or leading/trailing hyphens
• Cannot contain anthropic or claude
• Capability-focused (not agent-focused like -agent, -helper)

C. Description Quality

Structure:

• WHAT: Explains capabilities
• WHEN: States trigger conditions ("Use when...")
• TRIGGERS: Includes 3-5 keywords users would mention

Voice:

• Uses third-person (not "I can" or "you can")
• Within 1024 character limit

Anti-patterns:

• ❌ "Helps with files" → Too vague
• ❌ "I can help you..." → First-person
• ❌ "You can use this to..." → Second-person
• ❌ "An agent that..." → Agent-focused

D. File Structure

• SKILL.md exists
• All referenced files exist
• File paths use forward slashes
• Directory structure is logical (references/, scripts/, assets/)

E. Best Practices

• SKILL.md body under 500 lines
• Has Instructions section
• Has Examples section (recommended)
• Examples are concrete and runnable
• Single responsibility (one focused capability)
• Progressive disclosure (details in supporting files)
• Assumes Claude knows common concepts

Step 4: Run Review Checks

After validation passes, review for improvements:

Discoverability

• Is description maximally discoverable?
• Are trigger keywords comprehensive?
• Would Claude know when to activate?

Conciseness

• Does each paragraph justify its token cost?
• Could details move to supporting files?
• Is there over-explanation of common concepts?

Clarity

• Are instructions step-by-step and actionable?
• Are examples concrete and runnable?
• Is the structure logical and scannable?

Step 5: Generate Report

# Skill Check Report: [Skill Name]

## Summary
- **Status**: PASS / FAIL / WARNINGS
- **Location**: [path]
- **Issues**: [count critical] / [count warnings]

## Validation Results

### YAML Frontmatter
✅ | ❌ | ⚠️ [Status and details]

### Naming Conventions
✅ | ❌ | ⚠️ [Status and details]

### Description Quality
✅ | ❌ | ⚠️ [Status and details]

### File Structure
✅ | ❌ | ⚠️ [Status and details]

### Best Practices
✅ | ❌ | ⚠️ [Status and details]

## Critical Issues (must fix)
1. [Issue with specific fix]

## Warnings (should fix)
1. [Issue with specific fix]

## Improvement Suggestions
1. [Suggestion with before/after]

## Strengths
- [What's done well]

Step 6: Provide Specific Fixes

For each issue, show:

1. Current: What it is now
2. Problem: Why it's an issue
3. Fix: Specific improvement
4. Impact: How it helps

Example Fix: Vague Description

Current:

description: Helps with PDF files

Problem: Too vague, no triggers, missing capabilities

Fix:

description: Extracts text and tables from PDF files, fills forms, merges documents. Use when working with PDF files or when the user mentions PDFs, forms, or document extraction.

Impact: Specific capabilities, trigger conditions, discoverable keywords.

Example Fix: Wrong Voice

Current:

description: I can help you process data files and convert formats

Problem: First-person voice; descriptions inject into system prompt

Fix:

description: Processes data files and converts between formats (CSV, JSON, XML). Use when working with data files or format conversion.

Impact: Third-person voice, specific formats, trigger conditions.

Step 7: Apply Fixes (Optional)

Ask before making changes:

Found [N] issues:
- [Critical issues]
- [Warnings]
- [Suggestions]

Would you like me to apply these fixes?

If approved, use Edit to make changes.

Status Levels

• ✅ PASS: No issues
• ⚠️ WARNINGS: Non-critical issues that should be fixed
• ❌ FAIL: Critical issues that must be fixed

Priority Levels

Critical (must fix):

• Invalid YAML syntax
• Missing required fields
• Broken file references

Important (should fix):

• Vague descriptions
• Wrong voice (first/second person)
• Missing trigger keywords
• Poor naming

Nice-to-have:

• Additional examples
• Better organization
• Enhanced documentation

Troubleshooting

# Find all skills
find ~/.claude/skills .claude/skills -name "SKILL.md" 2>/dev/null

# Check for tabs in YAML
grep -P "\t" SKILL.md

# Find broken links
grep -oE '\[[^]]+\]\([^)]+\)' SKILL.md | while read link; do
  file=$(echo "$link" | sed 's/.*(\(.*\))/\1/')
  [ ! -f "$file" ] && echo "Missing: $file"
done

# View raw frontmatter
head -n 15 SKILL.md

Integration

After creating a skill:

skills-authoring → skills-check → iterate until passing

Before committing:

skills-check → fix critical issues → commit

Reference

For cross-tool compatibility and implementation details, see:

• Agent Skills Specification
• skills-authoring references