TLDRBEGINNER
What MCP Actually Does
The Model Context Protocol in plain terms — it is a port, not a plugin system, and that distinction explains most of the confusion.
MCP is a wire protocol for handing a model tools, data and prompts from an outside process. That is the whole idea.
The confusion comes from calling it a plugin system. A plugin runs inside your app. An MCP server runs beside it, as its own process, and speaks JSON-RPC over stdio or HTTP. Your agent is a client; the server owns the capability.
Three things a server can offer:
- Tools — functions the model may call.
- Resources — data the client may read.
- Prompts — reusable templates the user may invoke.
Why it matters: the same filesystem server works in any MCP-speaking client, and swapping the model changes nothing on the server side. That decoupling is the point — not the tool-calling, which already existed.