skillcheck-free

SkillCheck Free

Validate AI coding assistant skills against the agentskills specification. Works with Claude Code, Claude Desktop/Web, and Cursor. Catch issues before your users do.

Why SkillCheck?

Agent Skills are now an open standard adopted by Claude Code, Cursor, and dozens of coding agents. Your skill needs to work everywhere and follow best practices.

SkillCheck validates:

• Does the YAML frontmatter follow the spec?
• Will it trigger when users actually need it?
• Are the instructions clear and unambiguous?

Installation

Claude Code

The simplest path — use the skills CLI:

npx skills add olgasafonova/SkillCheck-Free

Or copy the folder manually:

cp -r skills/skill-check ~/.claude/skills/

Or clone directly:

git clone https://github.com/olgasafonova/SkillCheck-Free.git
cp -r SkillCheck-Free/skills/skill-check ~/.claude/skills/

Claude Desktop/Web (Projects)

1. Open claude.ai or Claude Desktop app
2. Create a new Project (or open an existing one)
3. Go to Project settings → Custom instructions
4. Copy the contents of skills/skill-check/SKILL.md (everything after the --- frontmatter)
5. Paste into the custom instructions field

No file installation needed - the skill runs directly from your Project instructions.

Cursor

Copy the rule file to your project's .cursor/rules directory:

mkdir -p .cursor/rules
cp cursor-rules/skill-check.mdc .cursor/rules/

Or clone directly:

git clone https://github.com/olgasafonova/SkillCheck-Free.git
mkdir -p .cursor/rules
cp SkillCheck-Free/cursor-rules/skill-check.mdc .cursor/rules/

Where to find SkillCheck-Free

SkillCheck-Free is listed in:

• skills.sh registry — install via npx skills add olgasafonova/SkillCheck-Free
• antigravity-awesome-skills — included in sickn33's 1,239+ universal agentic skills collection

Usage

In Claude Code, Claude Desktop/Web, or Cursor, say any of:

• "skillcheck my skill"
• "check skill at path/to/SKILL.md"
• "validate my skills"

Example Output

## SkillCheck Results: my-awesome-skill

### Summary
- Critical: 1 | Warnings: 2 | Suggestions: 3 | Passed: 44

### Critical Issues
**[1.2-desc-what]** Line 3: Description missing action verb
**Fix**: Start description with Create, Generate, Build, Convert, etc.

### Warnings
**[4.2-ambiguous-term]** Line 47: Vague term "several" found
**Fix**: Specify exact count or range

### Strengths
- Skill includes example section
- Skill documents prerequisites
- Description includes activation triggers

What It Checks

Structure (1.x)

Check	What It Catches
1.1-name	Invalid name format, reserved words
1.2-desc	Missing or weak description (WHAT verb + WHEN trigger recommended)
1.3-tools	Unknown or deprecated tool formats
1.4-category	Invalid category format
1.9-xml	XML angle brackets in frontmatter (prompt injection risk)
1.9-arg-hints	Missing argument-hint in frontmatter when $ARGUMENTS is used
1.10-readme	README.md inside skill folder (docs belong in SKILL.md)

Body (2.x)

Check	What It Catches
2.1-lines	File too long (500+ lines warning)
2.3-date	Hardcoded dates that will go stale
2.4-empty	Empty sections with no content
2.8-antipattern-format	Anti-pattern sections using prose instead of tables/bullets
2.9-mcp-tool-unqualified	Unqualified MCP tool names missing server prefix

Naming (3.x)

Check	What It Catches
3.1-vague	Generic names like "helper", "utils"
3.2-length	Names too short or too long
3.3-single	Single-word names lacking specificity
3.4-gerund	Gerund naming ("writing-helper" instead of verb-noun)