Plugin Structure

# Plugin Structure for Claude Code

## Overview

Claude Code plugins follow a standardized directory structure with automatic component discovery. Understanding this structure enables creating well-organized, maintainable plugins that integrate seamlessly with Claude Code.

**Key concepts:**
- Conventional directory layout for automatic discovery
- Manifest-driven configuration in `.claude-plugin/plugin.json`
- Component-based organization (commands, agents, skills, hooks)
- Portable path references using `${CLAUDE_PLUGIN_ROOT}`
- Explicit vs. auto-discovered component loading

## Directory Structure

Every Claude Code plugin follows this organizational pattern:

```
plugin-name/
├── .claude-plugin/
│   └── plugin.json          # Required: Plugin manifest
├── commands/                 # Slash commands (.md files)
├── agents/                   # Subagent definitions (.md files)
├── skills/                   # Agent skills (subdirectories)
│   └── skill-name/
│       └── SKILL.md         # Required for each skill
├── hooks/
│   └── hooks.json           # Event handler configuration
├── .mcp.json                # MCP server definitions
└── scripts/                 # Helper scripts and utilities
```

**Critical rules:**

1. **Manifest location**: The `plugin.json` manifest MUST be in `.claude-plugin/` directory
2. **Component locations**: All component directories (commands, agents, skills, hooks) MUST be at plugin root level, NOT nested inside `.claude-plugin/`
3. **Optional components**: Only create directories for components the plugin actually uses
4. **Naming convention**: Use kebab-case for all directory and file names

## Plugin Manifest (plugin.json)

The manifest defines plugin metadata and configuration. Located at `.claude-plugin/plugin.json`:

### Required Fields

```json
{
  "name": "plugin-name"
}
```

**Name requirements:**
- Use kebab-case format (lowercase with hyphens)
- Must be unique across installed plugins
- No spaces or special characters
- Example: `code-review-assistant`, `test-runner`, `api-docs`

### Recommended Metadata

```json
{
  "name": "plugin-name",
  "version": "1.0.0",
  "description": "Brief explanation of plugin purpose",
  "author": {
    "name": "Author Name",
    "email": "author@example.com",
    "url": "https://example.com"
  },
  "homepage": "https://docs.example.com",
  "repository": "https://github.com/user/plugin-name",
  "license": "MIT",
  "keywords": ["testing", "automation", "ci-cd"]
}
```

**Version format**: Follow semantic versioning (MAJOR.MINOR.PATCH)
**Keywords**: Use for plugin discovery and categorization

### Component Path Configuration

Specify custom paths for components (supplements default directories):

```json
{
  "name": "plugin-name",
  "commands": "./custom-commands",
  "agents": ["./agents", "./specialized-agents"],
  "hooks": "./config/hooks.json",
  "mcpServers": "./.mcp.json"
}
```

**Important**: Custom paths supplement defaults—they don't replace them. Components in both default directories and custom paths will load.

**Path rules:**
- Must be relative to plugin root
- Must start with `./`
- Cannot use absolute paths
- Support arrays for multiple locations

## Component Organization

### Commands

**Location**: `commands/` directory
**Format**: Markdown files with YAML frontmatter
**Auto-discovery**: All `.md` files in `commands/` load automatically

**Example structure**:
```
commands/
├── review.md        # /review command
├── test.md          # /test command
└── deploy.md        # /deploy command
```

**File format**:
```markdown
---
name: command-name
description: Command description
---

Command implementation instructions...
```

**Usage**: Commands integrate as native slash commands in Claude Code

### Agents

**Location**: `agents/` directory
**Format**: Markdown files with YAML frontmatter
**Auto-discovery**: All `.md` files in `agents/` load automatically

**Example structure**:
```
agents/
├── code-reviewer.md
├── test-generator.md
└── refactorer.md
```

**File format**:
```markdown
---
description: Agent role and expertise
capabilities:
  - Specific task 1
  - Specific task 2
---

Detailed agent instructions and knowledge...
```

**Usage**: Users can invoke agents manually, or Claude Code selects them automatically based on task context

### Skills

**Location**: `skills/` directory with subdirectories per skill
**Format**: Each skill in its own directory with `SKILL.md` file
**Auto-discovery**: All `SKILL.md` files in skill subdirectories load automatically

**Example structure**:
```
skills/
├── api-testing/
│   ├── SKILL.md
│   ├── scripts/
│   │   └── test-runner.py
│   └── references/
│       └── api-spec.md
└── database-migrations/
    ├── SKILL.md
    └── examples/
        └── migration-template.sql
```

**SKILL.md format**:
```markdown
---
name: Skill Name
description: When to use this skill
version: 1.0.0
---

Skill instructions and guidance...
```

**Supporting files**: Skills can include scripts, references, examples, or assets in subdirectories

**Usage**: Claude Code autonomously activates skills based on task context matching the description

### Hooks

**Location**: `hooks/hooks.json` or inline in `plugin.json`
**Format**: JSON configuration defining event handlers
**Registration**: Hooks register automatically when plugin enables

**Example structure**:
```
hooks/
├── hooks.json           # Hook configuration
└── scripts/
    ├── validate.sh      # Hook script
    └── check-style.sh   # Hook script
```

**Configuration format**:
```json
{
  "PreToolUse": [{
    "matcher": "Write|Edit",
    "hooks": [{
      "type": "command",
      "command": "bash ${CLAUDE_PLUGIN_ROOT}/hooks/scripts/validate.sh",
      "timeout": 30
    }]
  }]
}
```

**Available events**: PreToolUse, PostToolUse, Stop, SubagentStop, SessionStart, SessionEnd, UserPromptSubmit, PreCompact, Notification

**Usage**: Hooks execute automatically in response to Claude Code events

### MCP Servers

**Location**: `.mcp.json` at