What "MCP server" means

What MCP stands for

Model Context Protocol. The protocol is the standard; an MCP server is a program that speaks it. Almost nobody writes "Model Context Protocol server" in full — it is "MCP server", and often just "MCP".

Word by word

Model

The large language model doing the work — Claude, GPT, Gemini, or any other.

Context

Everything the model can see while it answers. A model cannot use what is not in its context; the protocol exists to put the right things there.

Protocol

A fixed message format — JSON-RPC 2.0 — that both sides implement once. Any client that speaks it can use any server that speaks it.

Server

The program on the providing side. Despite the name, it is often a small process on the same laptop as the client.

What it does not mean

Three things the name suggests that are not true.

Not a machine you rent

"Server" here is a software role, not hardware. Most MCP servers are a process on your own laptop that the client starts when you need it and stops when you quit.

Not a vendor plugin

The protocol is an open standard, so one server works with every client that speaks it. There is no store to submit to and no vendor approval to wait for.

Not an agent

A server exposes capabilities and waits. The model on the other side decides what to call and when. A server never starts anything itself.

How the term is used

• Two words, no hyphen: MCP server. The plural is MCP servers.
• "MCP" on its own usually means the protocol — "does Cursor support MCP?" — but you will also hear it used for a server, as in "I added three MCPs today". Both are common; only the first is precise.
• A server is named for what it provides, not where it runs: the Playwright MCP server, the GitHub MCP server, the Postgres MCP server.

In a sentence

• Add the Playwright MCP server and the agent can drive a browser.
• These docs are served over an MCP server, so the model cites the page it used.
• Is there an MCP server for Postgres?

Terms you will meet next to it

Words that turn up in the same sentence, defined once each. How the parts actually fit together is the companion page.

Host

The AI application you are using — Claude Code, Claude Desktop, Cursor.

Client

The connector inside the host holding one connection to one server. Error messages name it, so it is worth knowing.

Tool

One named function a server exposes, with a schema for its arguments and a description the model reads.

Tool call

The model invoking a tool part-way through an answer, and the result coming back to it.

Transport

How the two sides talk. stdio for a local process, HTTP for a URL.

stdio

Standard input and output. The host starts the server as a child process and pipes messages to it.

Handshake

The initialize exchange that opens a connection and settles which protocol revision both sides will use.

Registry

A public index of published servers. The official registry is upstream of most directories, which read from it.

Where the term comes from

Anthropic released the Model Context Protocol as an open standard in November 2024. The specification's own analogy is a USB-C port: one connector, many devices — one protocol, many tools. The term spread with the ecosystem: client support in Claude Code, Cursor and others, public registries, and thousands of published servers.

Other things called MCP

The acronym is older than the protocol and still belongs to several things. In any conversation about AI tooling it means Model Context Protocol, but a search for "MCP" on its own can land anywhere.

Master Control Program

The antagonist in Tron (1982).

Microsoft Certified Professional

A Microsoft certification, retired but still cited in older job listings.

Multi-Chip Package

Semiconductor packaging — several dies inside one package.

Model Context Protocol

The one this page is about. Anthropic, November 2024, released as an open standard.