# Skills Guide Skills are knowledge-layer components in Claude Code that provide domain-specific expertise and guidance to Claude. Unlike commands that require manual invocation, Skills are automatically activated based on task context. ## What are Skills? Skills are professional knowledge modules stored in `SKILL.md` files: - **Auto-activation**: Claude automatically uses relevant Skills based on task context - **Domain knowledge**: Provides best practices and guidance for specific domains - **Extensible**: Create custom Skills to meet specific needs - **Context-aware**: Only invoked in relevant scenarios ### Skills vs Commands vs Agents | Component | Trigger | Purpose | |-----------|---------|---------| | **Commands** | User manually invokes (`/command`) | Execute specific tasks | | **Skills** | Auto-activated | Provide domain knowledge | | **Agents** | Delegated calls | Handle complex workflows | ## Using Built-in Skills Claude Code plugins typically include multiple built-in Skills. When your task matches a Skill's description, Claude automatically uses it. ### Example: Code Review When you say "help me review this code for security issues", if a plugin with a security review Skill is installed, Claude will automatically apply that Skill's knowledge for the review. ### Viewing Available Skills Skills are typically installed with plugins: ```bash # Install plugin (plugins may contain multiple Skills) /plugin install plugin-name@marketplace ``` ## Creating Custom Skills ### Basic Structure The simplest Skill only needs a `SKILL.md` file: ```bash my-skill/ └── SKILL.md ``` ### SKILL.md Format ```markdown --- name: Code Style Guide description: Use this skill when the user asks about "code style", "naming conventions", "code formatting", or discusses coding standards version: 1.0.0 --- # Code Style Guide ## Naming Conventions - Variables use camelCase - Constants use UPPER_SNAKE_CASE - Classes use PascalCase - Private members use underscore prefix ## Formatting Rules - Use 2 spaces for indentation - Line width should not exceed 80 characters - Use trailing commas ## Best Practices - Functions should have single responsibility - Avoid deep nesting - Use meaningful variable names ``` ### Frontmatter Fields | Field | Required | Description | |-------|----------|-------------| | `name` | Yes | Skill name | | `description` | Yes | Trigger condition description (critical!) | | `version` | No | Version number | ### Writing Effective Descriptions The description field determines when a Skill is activated and should include specific trigger phrases: **Good example**: ```yaml description: Use this skill when the user asks to "create a hook", "add a PreToolUse hook", "validate tool use", or mentions hook events ``` **Bad example**: ```yaml description: Guide about hooks # Too vague ``` ## Complete Skill Structure For complex Skills, you can include more resources: ```bash my-skill/ ├── SKILL.md # Main knowledge document ├── references/ # Detailed references │ ├── patterns.md # Design patterns │ └── advanced.md # Advanced techniques ├── examples/ # Example code │ ├── basic.ts # Basic example │ └── advanced.ts # Advanced example └── scripts/ # Helper scripts └── validate.sh # Validation script ``` ### Referencing Resources Reference other resources in SKILL.md: ```markdown --- name: API Development Guide description: Use when the user asks about "API design", "REST interfaces", "API best practices" version: 1.0.0 --- # API Development Guide See @references/patterns.md for detailed API design patterns ## Quick Example See @examples/basic.ts for basic usage ``` ## Using Skills in Plugins ### Directory Structure Skills go in the plugin's `skills/` directory: ```bash my-plugin/ ├── .claude-plugin/ │ └── plugin.json ├── commands/ # Command layer ├── agents/ # Agent layer └── skills/ # Knowledge layer ├── code-style/ │ └── SKILL.md └── api-docs/ ├── SKILL.md └── references/ ``` ### Referencing Skills in Commands Commands can explicitly reference Skill knowledge: ```markdown --- description: Generate standards-compliant API documentation argument-hint: [api-file] --- Generate API documentation for @$1. Use the api-docs skill to ensure documentation includes: - Complete endpoint descriptions - Parameter specifications - Response formats - Error codes - Usage examples ``` ## Practical Examples ### Example 1: Project Standards Skill ```markdown --- name: Project Standards description: Use when the user asks about "project structure", "file organization", "directory conventions" version: 1.0.0 --- # Project Standards ## Directory Structure \`\`\` src/ ├── components/ # React components ├── hooks/ # Custom Hooks ├── services/ # API services ├── utils/ # Utility functions └── types/ # TypeScript types \`\`\` ## File Naming - Components: PascalCase (e.g., `UserProfile.tsx`) - Utilities: camelCase (e.g., `formatDate.ts`) - Constants: UPPER_SNAKE_CASE (e.g., `API_ENDPOINTS.ts`) ## Import Order 1. React related 2. Third-party libraries 3. Internal modules 4. Type definitions 5. Style files ``` ### Example 2: Git Workflow Skill ```markdown --- name: Git Workflow description: Use when the user asks about "branch strategy", "commit conventions", "Git process" version: 1.0.0 --- # Git Workflow Standards ## Branch Naming - Features: `feature/description` - Fixes: `fix/description` - Hotfixes: `hotfix/description` ## Commit Message Format \`\`\` ():