plugin-creator

name	plugin-creator
description	Create, validate, and publish Claude Code plugins and marketplaces. Use this skill when building plugins with commands, agents, hooks, MCP servers, or skills.

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": "[e-mail]"
  },
  "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": "[e-mail]"
  },
  "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

1. Create a GitHub repository
2. Add .claude-plugin/marketplace.json
3. Add plugin directories
4. 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:

1. Fork the repository
2. Add your plugin under plugins/
3. Update marketplace.json
4. Submit a pull request

Best Practices

Plugin Design

1. Single Responsibility: Each plugin should do one thing well
2. Clear Descriptions: Users should understand purpose from description
3. Sensible Defaults: Work out-of-the-box with minimal config
4. Version Semantics: Use semver (1.0.0, 1.1.0, 2.0.0)

Security

1. Minimal Permissions: Only request tools you need
2. No Secrets in Code: Use environment variables
3. Audit Hook Scripts: Review all shell scripts for safety
4. Document Risks: Explain what your plugin does

Documentation

1. README.md: Always include installation and usage
2. Examples: Show concrete use cases
3. Changelog: Track version changes
4. 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