Claude Code Plugin Development Skill

Expert knowledge for building Claude Code plugins with up-to-date 2025 standards.

When Claude Should Use This Skill

Activate this skill automatically when the user:

• •Asks to create/build a Claude Code plugin
• •Wants to write slash commands or Agent Skills
• •Needs to implement MCP servers or custom tools
• •Wants to configure hooks or event handlers
• •Asks about plugin architecture or structure
• •Needs help with plugin.json manifest
• •Wants to publish to a marketplace
• •Asks about debugging plugin components
• •Mentions keywords: plugin, skill, command, MCP, hook, marketplace, subagent

Quick Overview

Claude Code plugins consist of five component types that extend functionality:

1. •Slash Commands - User-triggered shortcuts (/command)
2. •Agent Skills - Model-invoked capabilities (auto-activated)
3. •Subagents - Specialized task handlers
4. •MCP Servers - External tool/data integrations
5. •Hooks - Event-driven automations

Documentation Structure

This skill is organized into focused modules for easy reference:

Core References

• •Plugin Structure - Architecture, file organization, component types, scope hierarchy
• •Plugin Manifest - plugin.json schema, validation, configuration
• •Slash Commands - Command creation, arguments, tool permissions, namespacing
• •Agent Skills - 2025 schema, activation patterns, descriptions that work
• •MCP Servers - Custom tools, TypeScript/Python implementations, tool naming
• •Hooks - Event handlers, available events, matchers, environment variables

Practical Guides

• •Development Workflow - Local testing, debugging, validation checklist
• •Publishing & Distribution - GitHub setup, versioning, marketplace creation
• •Best Practices - Security, performance, maintainability, design principles

Examples & Troubleshooting

• •Complete Plugin Examples - Full working examples for common use cases
• •Troubleshooting Guide - Common issues and solutions

Getting Started

For First-Time Plugin Creators

1. •Read Plugin Structure to understand architecture
2. •Create Plugin Manifest (required .claude-plugin/plugin.json)
3. •Choose component type(s) to implement:
   • •Commands? → See Slash Commands
   • •Skills? → See Agent Skills
   • •Tools? → See MCP Servers
   • •Automation? → See Hooks
4. •Follow Development Workflow for local testing
5. •Use Publishing Guide to distribute

For Specific Tasks

"I want to create a slash command" → See Slash Commands

"How do I make a skill that auto-activates?" → See Agent Skills - especially the "Activation Patterns" section

"I need to build custom tools/MCP server" → See MCP Servers

"How do I auto-format code after edits?" → See Hooks - PostToolUse event

"My skill isn't activating" → See Troubleshooting Guide - "Skills Not Activating" section

"What are the best practices?" → See Best Practices

Quick Reference

Minimal Plugin Structure

my-plugin/
├── .claude-plugin/
│   └── plugin.json              # REQUIRED
├── commands/                    # Optional
│   └── my-command.md
├── skills/                      # Optional
│   └── my-skill/
│       └── SKILL.md
├── mcp/                         # Optional
│   └── server.ts
└── README.md

Essential Commands

# Local testing
/plugin marketplace add ~/.claude/marketplaces/local
/plugin install my-plugin

# Management
/plugin list
/plugin update my-plugin
/help | grep my-command

# Validation
jq . .claude-plugin/plugin.json

Key 2025 Updates

• •✅ allowed-tools field for tool permissions in skills
• •✅ Version tracking required
• •✅ Enhanced activation triggers with specific keywords
• •✅ 240+ community plugins available

When to Reference Each Module

Important Notes

• •2025 Schema: All documentation follows the latest 2025 plugin schema
• •Activation Keywords: Skill descriptions must be specific with file types, actions, and tools
• •Tool Permissions: Use allowed-tools to restrict access appropriately
• •Testing First: Always test locally before publishing
• •No Secrets: Never commit API keys or credentials

Additional Resources

• •Official docs: https://code.claude.com/docs/en/plugins
• •Community marketplace: https://claudecodemarketplace.com
• •240+ plugins: https://github.com/jeremylongshore/claude-code-plugins-plus

Next Steps: Based on what the user is trying to build, direct them to the appropriate reference guide above. For comprehensive understanding, recommend reading in this order: Plugin Structure → Plugin Manifest → specific component type → Development Workflow → Publishing.