If you're using Claude Code, you've probably encountered three types of extensions: skills, plugins, and MCP servers. They all extend Claude's capabilities, but in fundamentally different ways. This guide clarifies the differences and helps you decide which to use.
What's the Quick Difference?
| Skills | Plugins | MCP Servers | |
|---|---|---|---|
| What it is | Knowledge file | Extension bundle | Tool interface |
| Adds | Expertise | Expertise + tools + automation | Tools only |
| Size | Single file | Multiple files | Separate process |
| Runtime | Prompt injection | Prompt + hooks + MCP | Separate server |
| Complexity | Low | Medium | Medium-High |
| Example | Code review checklist | Tailwind CSS Plugin (94K+ stars) | GitHub MCP Server (28K+ stars) |
What Are Skills and When Should You Use Them?
A skill is a markdown file with specialized instructions. When invoked, its content is injected into Claude's context, giving it domain-specific knowledge.
Example: A Code Review Skill contains instructions for how to conduct thorough code reviews — what to check, what patterns to look for, how to structure feedback.
When to use skills:
- You want to teach Claude a specific process or methodology
- You need Claude to follow particular conventions consistently
- You want reusable expertise across projects
- You need lightweight customization without installing tools
Skills are NOT:
- New tool capabilities (they can't access external systems)
- Autonomous processes (they're passive knowledge, not active agents)
- Heavyweight — they're single files, easy to create and share
Popular skills in our catalog:
- Code Review Skill — Structured review methodology
- Test Writer Skill — Test generation patterns
- Documentation Generator — Auto-generate docs from code
- Debug Investigator — Systematic debugging process
- Git Commit Skill — Conventional commit formatting
What Are Plugins and When Should You Use Them?
A plugin is a bundle that can contain skills, agents, hooks, MCP server configurations, and commands. Plugins are the most comprehensive extension type — they're like "apps" for Claude.
Example: The Tailwind CSS Plugin (94K+ stars) includes:
- Skills for utility-first CSS patterns and best practices
- Hooks that validate class names on save
- MCP server configurations for Tailwind's tooling
- Slash commands for common tasks
When to use plugins:
- You work with a specific technology (Next.js, Directus, Prisma, etc.)
- You want a complete solution, not just one skill
- You need automation (hooks) alongside knowledge
- You want slash commands for common workflows
Plugins are NOT:
- Simple knowledge files (they're structured packages with multiple components)
- Standalone tools (they enhance Claude, not replace it)
- One-size-fits-all (different plugins for different technologies)
Popular plugins in our catalog:
- Tailwind CSS Plugin (94K+ stars) — CSS framework
- Prettier Plugin (51K+ stars) — Code formatting
- Prisma Plugin (45K+ stars) — Database ORM
- Docker Plugin (5K+ stars) — Container management
For more detail, see: Claude Plugins: Everything You Need to Know
What Are MCP Servers and When Should You Use Them?
An MCP server is a separate process that exposes tools, resources, and prompts via the Model Context Protocol. MCP servers give Claude the ability to interact with external systems.
Example: The GitHub MCP Server (28K+ stars) gives Claude tools to:
- Create and manage pull requests
- Read and write issues
- Search code across repositories
- Review diffs and commits
When to use MCP servers:
- You need Claude to interact with external systems (databases, APIs, file systems)
- You want standardized tool access that works across AI platforms
- You need real-time data from APIs or databases
- You're building tools that should work with Claude, Cursor, and other MCP clients
MCP servers are NOT:
- Domain knowledge (they provide actions, not expertise)
- Claude-specific (they work with any MCP-compatible client)
- Heavyweight — most are simple npm packages
Most popular MCP servers:
- N8n (182K+ stars) — Workflow automation
- Filesystem (82K+ stars) — File management
- Puppeteer (82K+ stars) — Browser automation
- Context7 (51K+ stars) — Documentation context
For setup instructions, see: How to Set Up MCP Servers with Claude Desktop
How Do They Work Together?
The real power comes from combining all three:
Plugin: nextjs-dev
├─ Skill: App Router patterns (knowledge)
├─ Skill: Data fetching best practices (knowledge)
├─ Hook: Auto-lint on file save (automation)
└─ MCP: Next.js DevTools server (tools)
The plugin bundles everything together. Skills provide the knowledge of how to build Next.js apps correctly. MCP servers provide the tools to interact with the dev server, inspect components, and run builds. Hooks provide automation for repetitive tasks like linting and formatting.
A typical project might use:
- 1-2 plugins for your tech stack (e.g.,
nextjs-dev+directus-dev) - 3-5 MCP servers for tool access (filesystem, GitHub, database)
- 5-10 skills for specific tasks (code review, testing, deployment)
Which Should You Choose?
Use this decision guide:
- Need Claude to know something? → Use a skill
- Need Claude to do something with an external system? → Use an MCP server
- Need a complete solution for a technology? → Use a plugin
- Need automated actions on events? → Use a plugin with hooks
- Building for multiple AI tools (Claude + Cursor)? → Use MCP servers (protocol-level, tool-agnostic)
Can You Use All Three at Once?
Yes — and you should. The three types are complementary, not competing:
- Skills teach Claude what to do (knowledge layer)
- MCP servers give Claude tools to do it (capability layer)
- Plugins combine both and add automation (integration layer)
For example, a full-stack development setup might look like:
| Layer | Tools | Purpose |
|---|---|---|
| Knowledge | Skills for code review, testing, deployment | Claude knows best practices |
| Tools | Filesystem, GitHub, database MCP servers | Claude can read/write code and data |
| Integration | Stack plugins for your frameworks | Everything works together seamlessly |
Where Can You Find Them?
All three types are available in our catalog, aggregated from 21+ sources:
- Skills — Individual expertise files
- Plugins — Complete extension packages
- MCP Servers — Tool interfaces
Use filters to sort by popularity, freshness, and platform support.
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