# Revision: Cheat Sheet and Self-Check — Claude Code Skills & SKILL.md

Source: https://www.geekswithgeeks.com/en/claude-code-skills/z-revision

> Review the key ideas of the whole course.

## Cheat sheet

**What**: a skill = folder + `SKILL.md` (YAML frontmatter `name` + `description`, then Markdown instructions) + optional scripts, references, templates; progressive disclosure: descriptions always loaded, body when relevant, extra files/scripts only when needed. **Vs others**: CLAUDE.md = always-on facts; skill = on-demand procedure; slash command = prompt you trigger; subagent = separate context; MCP = external tools; hook = deterministic enforcement. **Write**: one job per skill; lowercase-hyphen `name` matching the folder (<= 64 chars); description <= 1024 chars saying what, when, and trigger phrases; body with steps, outputs, verification, gotchas; < ~500 lines, details in `references/`. **Files**: reference each file by relative path and say when to read it; scripts for exact work (clear args, concise JSON, exit codes, helpful errors); `allowed-tools` as narrow as possible. **Use**: personal `~/.claude/skills`, project `.claude/skills` (git), plugins; chosen automatically by description or invoked by name/slash; share and version like code, update with the process. **Test**: should / should-not prompts, script fixtures, read transcripts, change one thing at a time. **Security**: scripts run with your permissions, so review third-party skills fully, pin versions, prefer sandboxes, no secrets in files, treat fetched content as data, confirm before destructive actions; scanning never replaces reading. **Patterns**: review checklists with cited evidence, "look at it" verification loops, templates and workflows with approval gates; avoid vague descriptions, giant bodies and rules that need a hook. Details of Claude Code evolve, so check the official documentation.

**Quiz:** Your skill never triggers. You have already checked the folder name and frontmatter. What next?

- [x] Rewrite the description with what, when and the exact phrases users say, then test with real prompts
- [ ] Make the body longer
- [ ] Delete the skill
- [ ] Rename the folder randomly

*Answer:* Rewrite the description with what, when and the exact phrases users say, then test with real prompts. Selection depends mainly on the description.

**Quiz:** You are asked to install a public skill whose setup says to run a downloaded script piped into bash. What do you do?

- [ ] Paste your tokens into it
- [ ] Run it immediately
- [ ] Pre-approve all Bash tools
- [x] Refuse or inspect the script fully first; run unfamiliar code only in a sandbox without credentials

*Answer:* Refuse or inspect the script fully first; run unfamiliar code only in a sandbox without credentials. Download-and-execute with your permissions is a classic compromise route.

**Quiz:** Which content belongs in CLAUDE.md rather than in a skill?

- [ ] A rarely used 20-step deployment procedure
- [x] Facts and rules needed in every session, such as the test command and conventions
- [ ] A large API reference
- [ ] A one-off migration script

*Answer:* Facts and rules needed in every session, such as the test command and conventions. Always-needed context goes in memory; on-demand procedures go in skills.