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)
- Open claude.ai or Claude Desktop app
- Create a new Project (or open an existing one)
- Go to Project settings → Custom instructions
- Copy the contents of
skills/skill-check/SKILL.md (everything after the --- frontmatter)
- 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:
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) |
