Claude Code Plugin Creator Skill

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:

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."

Agent Skills: Claude Code Plugin Creator

Install this agent skill to your local

Skill Files