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:

• Manifest location: The plugin.json manifest MUST be in .claude-plugin/ directory

• Component locations: All component directories (commands, agents, skills, hooks) MUST be at plugin root level, NOT nested inside .claude-plugin/

• Optional components: Only create directories for components the plugin actually uses

• 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

{

  "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

{

  "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):

{

  "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:

---

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:

---

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:

---

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:

{

  "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 plugin root or inline in plugin.json

Format: JSON configuration for MCP server definitions

Auto-start: Servers start automatically when plugin enables

Example format:

{

  "mcpServers": {

    "server-name": {

      "command": "node",

      "args": ["${CLAUDE_PLUGIN_ROOT}/servers/server.js"],

      "env": {

        "API_KEY": "${API_KEY}"

      }

    }

  }

}

Usage: MCP servers integrate seamlessly with Claude Code's tool system

Portable Path References

${CLAUDE_PLUGIN_ROOT}

Use ${CLAUDE_PLUGIN_ROOT} environment variable for all intra-plugin path references:

{

  "command": "bash ${CLAUDE_PLUGIN_ROOT}/scripts/run.sh"

}

Why it matters: Plugins install in different locations depending on:

• User installation method (marketplace, local, npm)

• Operating system conventions

• User preferences

Where to use it:

• Hook command paths

• MCP server command arguments

• Script execution references

• Resource file paths

Never use:

• Hardcoded absolute paths (/Users/name/plugins/...)

• Relative paths from working directory (./scripts/... in commands)

• Home directory shortcuts (~/plugins/...)

Path Resolution Rules

In manifest JSON fields (hooks, MCP servers):

"command": "${CLAUDE_PLUGIN_ROOT}/scripts/tool.sh"

In component files (commands, agents, skills):

Reference scripts at: ${CLAUDE_PLUGIN_ROOT}/scripts/helper.py

In executed scripts:

#!/bin/bash

# ${CLAUDE_PLUGIN_ROOT} available as environment variable

source "${CLAUDE_PLUGIN_ROOT}/lib/common.sh"

File Naming Conventions

Component Files

Commands: Use kebab-case .md files

• code-review.md → /code-review

• run-tests.md → /run-tests

• api-docs.md → /api-docs

Agents: Use kebab-case .md files describing role

• test-generator.md

• code-reviewer.md

• performance-analyzer.md

Skills: Use kebab-case directory names

• api-testing/

• database-migrations/

• error-handling/

Supporting Files

Scripts: Use descriptive kebab-case names with appropriate extensions

• validate-input.sh

• generate-report.py

• process-data.js

Documentation: Use kebab-case markdown files

• api-reference.md

• migration-guide.md

• best-practices.md

Configuration: Use standard names

• hooks.json

• .mcp.json

• plugin.json

Auto-Discovery Mechanism

Claude Code automatically discovers and loads components:

• Plugin manifest: Reads .claude-plugin/plugin.json when plugin enables

• Commands: Scans commands/ directory for .md files

• Agents: Scans agents/ directory for .md files

• Skills: Scans skills/ for subdirectories containing SKILL.md

• Hooks: Loads configuration from hooks/hooks.json or manifest

• MCP servers: Loads configuration from .mcp.json or manifest

Discovery timing:

• Plugin installation: Components register with Claude Code

• Plugin enable: Components become available for use

• No restart required: Changes take effect on next Claude Code session

Override behavior: Custom paths in plugin.json supplement (not replace) default directories

Best Practices

Organization

-

Logical grouping: Group related components together

• Put test-related commands, agents, and skills together

• Create subdirectories in scripts/ for different purposes

-

Minimal manifest: Keep plugin.json lean

• Only specify custom paths when necessary

• Rely on auto-discovery for standard layouts

• Use inline configuration only for simple cases

-

Documentation: Include README files

• Plugin root: Overall purpose and usage

• Component directories: Specific guidance

• Script directories: Usage and requirements

Naming

-

Consistency: Use consistent naming across components

• If command is test-runner, name related agent test-runner-agent

• Match skill directory names to their purpose

-

Clarity: Use descriptive names that indicate purpose

• Good: api-integration-testing/, code-quality-checker.md

• Avoid: utils/, misc.md, temp.sh

-

Length: Balance brevity with clarity

• Commands: 2-3 words (review-pr, run-ci)

• Agents: Describe role clearly (code-reviewer, test-generator)

• Skills: Topic-focused (error-handling, api-design)

Portability

• Always use ${CLAUDE_PLUGIN_ROOT}: Never hardcode paths

• Test on multiple systems: Verify on macOS, Linux, Windows

• Document dependencies: List required tools and versions

• Avoid system-specific features: Use portable bash/Python constructs

Maintenance

• Version consistently: Update version in plugin.json for releases

• Deprecate gracefully: Mark old components clearly before removal

• Document breaking changes: Note changes affecting existing users

• Test thoroughly: Verify all components work after changes

Common Patterns

Minimal Plugin

Single command with no dependencies:

my-plugin/

├── .claude-plugin/

│   └── plugin.json    # Just name field

└── commands/

    └── hello.md       # Single command

Full-Featured Plugin

Complete plugin with all component types:

my-plugin/

├── .claude-plugin/

│   └── plugin.json

├── commands/          # User-facing commands

├── agents/            # Specialized subagents

├── skills/            # Auto-activating skills

├── hooks/             # Event handlers

│   ├── hooks.json

│   └── scripts/

├── .mcp.json          # External integrations

└── scripts/           # Shared utilities

Skill-Focused Plugin

Plugin providing only skills:

my-plugin/

├── .claude-plugin/

│   └── plugin.json

└── skills/

    ├── skill-one/

    │   └── SKILL.md

    └── skill-two/

        └── SKILL.md

Troubleshooting

Component not loading:

• Verify file is in correct directory with correct extension

• Check YAML frontmatter syntax (commands, agents, skills)

• Ensure skill has SKILL.md (not README.md or other name)

• Confirm plugin is enabled in Claude Code settings

Path resolution errors:

• Replace all hardcoded paths with ${CLAUDE_PLUGIN_ROOT}

• Verify paths are relative and start with ./ in manifest

• Check that referenced files exist at specified paths

• Test with echo $CLAUDE_PLUGIN_ROOT in hook scripts

Auto-discovery not working:

• Confirm directories are at plugin root (not in .claude-plugin/)

• Check file naming follows conventions (kebab-case, correct extensions)

• Verify custom paths in manifest are correct

• Restart Claude Code to reload plugin configuration

Conflicts between plugins:

• Use unique, descriptive component names

• Namespace commands with plugin name if needed

• Document potential conflicts in plugin README

• Consider command prefixes for related functionality

For detailed examples and advanced patterns, see files in references/ and examples/ directories.