Claude Code ships with solid built-in capabilities, but skills let you push it further. A skill is a packaged set of instructions that an agent loads on demand — install a code review skill and Claude Code runs structured PR reviews. Add a security auditor and it scans for OWASP Top 10 vulnerabilities. No prompt engineering required.

Here’s how to find the right skill, install it, and verify it works.

What is a skill, exactly?

A skill is a markdown file — usually a CLAUDE.md or a set of instructions — that gets loaded into Claude Code’s context when you invoke it. Unlike MCP servers, which give agents access to external tools and APIs, skills change how the agent behaves. They add domain knowledge, workflows, and repeatable processes.

Think of MCP servers as giving your agent new hands. Skills give it new expertise.

Most skills live on GitHub and install with a single command. Once installed, the skill is available in your project or globally, depending on configuration.

Step 1: Find a skill

The AgentNDX skills directory lists verified skills across categories like engineering, security, content, data, and product management. Each listing shows compatible agents, install commands, and use cases.

You can also browse GitHub repos that package skills directly. Some popular sources:

For this walkthrough, we’ll install the Code Reviewer skill.

Step 2: Install the skill

The standard install command uses gh skill install:

gh skill install wshobson/agents/code-reviewer

This pulls the skill from GitHub and registers it with Claude Code. The skill files land in your project — typically as a CLAUDE.md entry or a dedicated skill file that Claude Code reads at session start.

For official Anthropic skills, same pattern:

gh skill install anthropics/skills/web-app-tester

Some skills support global installation (available in every project) or project-scoped installation (only in the current repo). Check the skill’s README for specifics. Most install at the project level by default.

Step 3: Verify the installation

After installing, open a new Claude Code session in your project directory. The skill should show up when you run /help or check available skills.

To test it, invoke directly:

/code-reviewer

Or just ask Claude Code to do what the skill handles:

“Review the changes in my current branch for bugs and security issues.”

If the skill loaded correctly, you’ll see it follow the structured review workflow instead of default behavior — severity ratings, specific fixes, the whole process laid out.

Step 4: Manage your skills

List what’s installed, remove what you don’t need, update to latest.

To see what’s installed:

gh skill list

To remove a skill:

gh skill remove code-reviewer

To update:

gh skill update code-reviewer

Project vs global skills

Some skills belong everywhere. A code reviewer or security auditor adds value in any repo — install those globally.

Others are project-specific. A skill that knows your team’s PR conventions or your company’s compliance rules should stay scoped to that project.

Rule of thumb: if you’d use it in every repo, go global. If it carries domain-specific knowledge, keep it project-scoped.

Skills vs MCP servers

Both skills and MCP servers extend what Claude Code can do. The difference is what they extend.

MCP servers connect Claude Code to external systems. A database MCP server lets your agent query a database. A browser MCP server lets it interact with web pages. The server provides tools the agent calls.

Skills change behavior and knowledge. A code review skill doesn’t connect to anything external — it teaches Claude Code a review process with specific criteria, severity ratings, and output formats. Claude Code already knew how to review code. The skill makes it consistent.

In practice, you’ll use both. An MCP server provides the data access, a skill provides the process for working with that data.

FAQ

Do skills work with agents other than Claude Code? Depends on the skill. Many in the AgentNDX directory list compatible agents — some work with Codex, Cursor, Windsurf, and others. Some are Claude Code-only. Check the “Compatible with” field before installing.

Can I write my own? Yes. A skill is just a structured set of instructions. Create a CLAUDE.md with your workflows, review criteria, or domain knowledge and Claude Code will follow it. For a full guide, see How to Write Your Own Claude Code Skill from Scratch.

Do skills cost anything? Most are free and open-source. Some advanced skills are marked “Pro” and may require a paid subscription to the provider. The AgentNDX directory labels each skill’s pricing tier so you know before you install.