Claude Code Plugin Creator

Overview

This skill provides comprehensive guidance for creating Claude Code plugins following the official Anthropic format (as of December 2025).

Plugin Architecture

A Claude Code plugin can contain any combination of:

• Commands: Custom slash commands (/mycommand )

• Agents: Specialized AI subagents for specific tasks

• Hooks: Pre/post tool execution behaviors

• MCP Servers: Model Context Protocol integrations

• Skills: Domain-specific knowledge packages

Directory Structure

my-plugin/ ├── .claude-plugin/ │ └── plugin.json # REQUIRED - Plugin manifest ├── commands/ # Optional - Slash commands │ └── my-command.md ├── agents/ # Optional - Subagents │ └── my-agent.md ├── hooks/ # Optional - Hook definitions │ └── hooks.json ├── skills/ # Optional - Bundled skills │ └── my-skill/ │ └── SKILL.md ├── mcp/ # Optional - MCP server configs └── README.md

Plugin Manifest (plugin.json)

The .claude-plugin/plugin.json file is required. Here's the complete schema:

{ "$schema": "https://anthropic.com/claude-code/plugin.schema.json", "name": "my-plugin", "version": "1.0.0", "description": "Clear description of what this plugin does", "author": { "name": "Your Name", "email": "you@example.com" }, "license": "MIT", "commands": [ { "name": "mycommand", "description": "What this command does", "source": "./commands/my-command.md" } ], "agents": [ { "name": "my-agent", "description": "What this agent specializes in", "source": "./agents/my-agent.md" } ], "hooks": { "source": "./hooks/hooks.json" }, "skills": [ "./skills/my-skill" ], "mcp_servers": [ { "name": "my-mcp", "command": "npx", "args": ["my-mcp-server"] } ] }

Creating Commands

Commands are markdown files with YAML frontmatter:

name: deploy description: Deploy the application to production

Deploy Command

When the user runs /deploy, perform these steps:

1. Run the build process
2. Run all tests
3. Create a deployment package
4. Upload to the configured target

Usage Examples

• /deploy - Deploy to default environment
• /deploy staging - Deploy to staging
• /deploy production --skip-tests - Deploy to production (use carefully)

Creating Agents

Agents are specialized subagents with focused capabilities:

name: security-reviewer description: Reviews code for security vulnerabilities model: sonnet tools:

• Read
• Grep
• Glob

Security Review Agent

You are a security expert focused on identifying vulnerabilities.

Your Responsibilities

1. Scan for OWASP Top 10 vulnerabilities
2. Identify hardcoded secrets
3. Check for input validation issues
4. Review authentication/authorization logic

Output Format

Provide findings as:

• CRITICAL: Immediate security risk
• HIGH: Should fix before deployment
• MEDIUM: Fix in next sprint
• LOW: Consider improving

Creating Skills

Skills use the official Agent Skills format:

name: my-skill description: What this skill teaches Claude to do

My Skill Name

When to Use

Use this skill when the user needs help with [specific task].

Instructions

1. Step one
2. Step two
3. Step three

Examples

Example 1: Basic Usage

[Concrete example]

Example 2: Advanced Usage

[Another example]

Best Practices

• Practice 1
• Practice 2

Creating Hooks

Hooks are defined in hooks.json :

{ "hooks": [ { "event": "PreToolUse", "matcher": "Edit|Write", "command": ".claude-plugin/hooks/security-check.sh" }, { "event": "PostToolUse", "matcher": "Bash", "command": ".claude-plugin/hooks/log-commands.sh" } ] }

Hook events:

• PreToolUse

• Before a tool executes

• PostToolUse

• After a tool completes

• SessionStart

• When a Claude Code session begins

• SessionEnd

• When a session ends

Creating a Marketplace

To distribute multiple plugins, create a marketplace:

my-marketplace/ ├── .claude-plugin/ │ └── marketplace.json └── plugins/ ├── plugin-a/ │ └── .claude-plugin/ │ └── plugin.json └── plugin-b/ └── .claude-plugin/ └── plugin.json

marketplace.json

{ "$schema": "https://anthropic.com/claude-code/marketplace.schema.json", "name": "my-marketplace", "version": "1.0.0", "description": "Collection of productivity plugins", "owner": { "name": "Your Name", "email": "you@example.com" }, "plugins": [ { "name": "plugin-a", "description": "What plugin A does", "source": "./plugins/plugin-a", "category": "development", "tags": ["productivity", "automation"] }, { "name": "plugin-b", "description": "What plugin B does", "source": "./plugins/plugin-b", "category": "productivity" } ] }

Plugin Categories

Official categories:

• development

• Developer tools

• productivity

• Workflow automation

• security

• Security tools

• learning

• Educational content

• testing

• Test automation

• database

• Database tools

• design

• UI/UX tools

• monitoring

• Observability

• deployment

• CI/CD tools

Testing Plugins

Local Testing

Install from local path

/plugin install /path/to/my-plugin

Or add as local marketplace

/plugin marketplace add /path/to/my-marketplace /plugin install my-plugin@my-marketplace

List installed plugins

/plugin list

Enable/disable

/plugin enable my-plugin /plugin disable my-plugin

Uninstall

/plugin uninstall my-plugin

Validation Checklist

Before publishing, verify:

• plugin.json is valid JSON

• All source paths exist

• Commands have name + description

• Agents specify required tools

• Hook scripts are executable

• Skills have proper YAML frontmatter

• README.md explains usage

Publishing to a Marketplace

Option 1: Create Your Own Marketplace

• Create a GitHub repository

• Add .claude-plugin/marketplace.json

• Add plugin directories

• Users install via: /plugin marketplace add your-username/your-repo /plugin install plugin-name@your-repo

Option 2: Submit to Community Marketplaces

Popular community marketplaces:

• cc-marketplace

• claude-plugins.dev

Submit via:

• Pull request to the marketplace repo

• Or their submission forms

Option 3: Anthropic's Official Marketplace

The anthropics/claude-code repo contains official plugins. To add:

• Fork the repository

• Add your plugin under plugins/

• Update marketplace.json

• Submit a pull request

Best Practices

Plugin Design

• Single Responsibility: Each plugin should do one thing well

• Clear Descriptions: Users should understand purpose from description

• Sensible Defaults: Work out-of-the-box with minimal config

• Version Semantics: Use semver (1.0.0, 1.1.0, 2.0.0)

Security

• Minimal Permissions: Only request tools you need

• No Secrets in Code: Use environment variables

• Audit Hook Scripts: Review all shell scripts for safety

• Document Risks: Explain what your plugin does

Documentation

• README.md: Always include installation and usage

• Examples: Show concrete use cases

• Changelog: Track version changes

• License: Specify usage terms (MIT recommended)

Quick Start Template

Run this to scaffold a new plugin:

mkdir my-plugin && cd my-plugin mkdir -p .claude-plugin commands agents skills

cat > .claude-plugin/plugin.json << 'EOF' { "name": "my-plugin", "version": "1.0.0", "description": "My awesome Claude Code plugin", "author": { "name": "Your Name" }, "commands": [] } EOF

cat > README.md << 'EOF'

My Plugin

Description of your plugin.

Installation

/plugin install /path/to/my-plugin

Usage

Describe how to use your plugin. EOF

echo "Plugin scaffolded! Edit .claude-plugin/plugin.json to add commands/agents."

References

• Claude Code Plugin Docs

• Creating Marketplaces

• Agent Skills Spec

• Anthropic Skills Repo

• Official Plugins