Claude Code Skills & SKILL.md
Package your know-how as reusable skills: SKILL.md structure, descriptions that trigger, supporting scripts and references, testing, security review and team sharing, with validators and a script harness you can run.
Syllabus
What Skills Are
- The Problem Skills Solve
- Anatomy of a Skill: Folder, SKILL.md, Frontmatter, Body
- Progressive Disclosure: Why Skills Stay Cheap
- Skills vs CLAUDE.md, Commands, Subagents, MCP and Hooks
Writing a Good SKILL.md
- Choosing a Name and Scope
- The Description: Your Most Important Sentence
- Structuring the Body: Steps, Examples, Gotchas
Scripts, References and Templates
- Folder Layout and Loading Rules
- Keeping SKILL.md Short and Details in References
- Scripts: Deterministic Work Inside a Skill
- allowed-tools and Least Privilege
Where Skills Live and How They Run
- Personal, Project and Plugin Skills
- Automatic and Explicit Invocation
- Sharing, Versioning and Maintaining Skills
Testing and Improving Skills
- Testing Triggering With Should and Should-Not Prompts
- Testing Scripts Like Normal Code
- Improving From Real Transcripts
Security and Trust
- The Risks of Third-Party Skills
- A Review Checklist Before Installing or Merging a Skill
- Writing Safe Skills: Secrets, Injection and Isolation
Patterns and Recipes
- Checklist and Review Skills
- "Look at It" Skills: Closing the Verification Loop
- Template and Workflow Skills
- Anti-Patterns and When Not to Use a Skill