Claude Code Plugin vs Skill vs MCP: A Clear Disambiguation
Plugins, skills, and MCP servers are the three ways to extend Claude Code, and they are constantly conflated. A clear table of scope, lifecycle, and distribution.
Three terms get used interchangeably when people talk about extending Claude Code: plugin, skill, and MCP server. They are not the same thing. They operate at different layers, load at different times, and ship through different channels. Conflating them leads to bad architecture decisions — packaging a one-off instruction as an MCP server, or reaching for a plugin when a skill would do.
This post draws the lines cleanly. Each primitive answers a different question: a skill answers "what should the model know how to do," an MCP server answers "what external systems can the model reach," and a plugin answers "how do I distribute a bundle of capabilities to a team."
The one-line definitions
- A skill is a packaged unit of procedural knowledge — a
SKILL.mdfile (plus optional scripts and references) that teaches the model how to perform a task. It is loaded on demand when the task is relevant. (Agent Skills documentation) - An MCP server is a separate process that exposes tools, resources, and prompts over the Model Context Protocol, an open standard for connecting AI applications to external systems. It is how the model reaches databases, APIs, and services. (MCP in Claude Code)
- A plugin is a distributable bundle that can contain commands, agents, skills, hooks, and MCP server configuration, installed as a single unit and shared across a team via a marketplace. (Claude Code plugins documentation)
Plugin vs Skill vs MCP: the disambiguation table
| Dimension | Skill | MCP server | Plugin |
|---|---|---|---|
| What it is | Packaged procedural knowledge (SKILL.md + assets) |
A process exposing tools, resources, and prompts over an open protocol | A distributable bundle of commands, agents, skills, hooks, and MCP config |
| Scope | Teaches the model how to do a task | Connects the model to external systems and data | Packages and distributes many capabilities at once |
| Lifecycle | Loaded on demand when the task is relevant | Runs as a long-lived process; connected for the session | Installed once; its contents load per their own rules |
| Runs where | In-context, no separate process | A separate local or remote process | N/A — a container; its parts run per their type |
| Distribution | A directory or repo; bundled inside plugins | Configured per project or user; published to MCP registries | Installed from a plugin marketplace |
| Answers | "What should the model know how to do?" | "What systems can the model reach?" | "How do I ship a capability set to a team?" |
The key insight: these are composable, not competing. A plugin can ship skills and wire up MCP servers. A skill can describe how to use the tools an MCP server exposes. You rarely choose one instead of another — you choose which layer a given capability belongs to.
How to choose
- Reach for a skill when you are encoding a repeatable procedure — a workflow, a checklist, a domain method — that the model should apply when relevant. No new process, no external connection.
- Reach for an MCP server when the model needs to touch something outside itself: query a database, call an API, read a file store, hit a SaaS product. If it requires authentication or a network call to a system, it is an MCP concern.
- Reach for a plugin when you have a set of capabilities — several commands, a few agents, a handful of skills, maybe an MCP server — that you want to install and version as one unit and share with a team.
For a ranked, opinionated tour of what is actually worth installing across all three, see Best Claude Code Plugins 2026. For the deeper distinction between portable skill libraries and end-to-end workflow plugins — the two dominant shapes a plugin takes — read Skill Libraries vs. Workflow Plugins.
Soleur itself is a plugin: it ships 67 agents and 83 skills across 8 departments, and configures the MCP servers its agents rely on — one install, the whole Company-as-a-Service organization.
Frequently asked questions
What is the difference between a Claude Code plugin, skill, and MCP server?
A skill is packaged procedural knowledge that teaches the model how to do a task and loads on demand. An MCP server is a separate process that connects the model to external systems and data over an open protocol. A plugin is a distributable bundle that can contain commands, agents, skills, hooks, and MCP server configuration, installed as a single unit. They operate at different layers and are composable, not competing.
When should I use a skill instead of an MCP server?
Use a skill when you are encoding a repeatable procedure the model should apply when relevant, with no external connection required. Use an MCP server when the model needs to reach something outside itself, such as a database, an API, or a SaaS product, which requires a running process and usually authentication. Skills teach know-how; MCP servers provide reach.
Can a plugin contain skills and MCP servers?
Yes. A plugin is a container. It can bundle commands, agents, skills, hooks, and MCP server configuration and install them all as one versioned unit. This is why the three primitives are composable rather than mutually exclusive: the plugin is the distribution layer, while skills and MCP servers are the capability layers inside it.
Which one do I distribute to my team?
Distribute a plugin. Plugins install from a marketplace as a single versioned unit and can carry many skills, agents, and MCP server configurations at once, so a team installs one thing and gets the whole capability set. Individual skills and MCP servers can be shared on their own, but a plugin is the channel built for packaging and sharing a set of capabilities.
