Enhancing Skills
You learned how you can add custom skills.
If you find that your custom skills are not getting used by Claude Code, try tweaking the description of the skill - because, as explained, it's the title + description that's exposed to Claude Code and that therefore is important for its "automatic discoverability".
You can try adding extra instructions like "Use this skill to optimize React components and check for the usage of common best practices" or "Gets triggered when writing ANY kind of CSS code".
If you DON'T want automatic invocation (i.e., if you want to use skills as custom commands only), you can add disable-model-invocation: true to the skill metadata (i.e., next to title and description). If you want the opposite (i.e., ONLY automatic discoverability, NO user invocation) you can add user-invocable: false.
You can also restrict which tools Claude Code may use when triggering this skill - via the allowed-tools metadata. For example, adding allowed-tools: Read allows Claude Code to read files but prevents it from editing or creating. You find a list of available tools here.
If your skill should work with extra input (e.g., when building it as a custom command), you can use the special $ARGUMENTS placeholder in your skill content.
For example, you could build a specialized code-review skill like this:
.claude/skills/code-review/SKILL.md:
--- name: code-review description: Review code for bugs, security or performance issues. Use this skill when asked to perform code reviews or after finishing major tasks or after refactoring code. allowed-tools: Read description: Perform a code-review --- MODE: $ARGUMENTS If Mode is one of the following, adjust the review as described: - MODE == BUGS: Focus ONLY on logical or other bugs. - MODE == SECURITY: Focus ONLY on security issues. - MODE = PERFORMANCE: Focus ONLY performance issues. MODE can also be set to a combination like "BUGS,SECURITY" etc => Perform the combined review in that case. If MODE is set to anything else or nothing at all, perform a thorough, general code review. Perform an in-depth code review of the entire codebase. Carefully and thoroughly explore the codebase file-by-file to find potential issues and improvements. Don't rush it, instead make sure you fully understand the code structure and architecture. Create a detailed report of all your findings.
You'll also see a different way of creating custom commands later in the course.
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Adding Third-Party Skills
Building custom skills is a powerful ability, because it allows you to really tailor your Claude Code experience & behavior to your specific (project) requirements and preferences.
But you can also add third-party skills - of course also in addition to your custom skills.
A popular and growing (free!) public skills repository is skills.sh.
There, you find a broad selection of skills you can add to your project. You can install skills from that repository into your project via npx skills add <owner/repo> (requires Node.js to be installed on your system, since npx is a tool installed together with Node.js).
Of course, you can and should explore those skills you installed. You can tweak them or remove selected parts of the skills.