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What MCP servers are

What MCP servers are

MCP stands for Model Context Protocol. It is a standard way to plug extra tools and data sources into Claude Code. Instead of building every integration into the CLI, Claude talks to small external programs called MCP servers, and each server exposes a set of tools Claude can call.

A server can wrap almost anything: your filesystem, a database, a ticketing system, a browser, an internal API. Once a server is connected, its tools show up alongside Claude's built-in ones and Claude can use them during a session.

Adding a server

You register a server with claude mcp add. The part after -- is the command Claude runs to start the server:

bash
claude mcp add files -- npx -y @modelcontextprotocol/server-filesystem /root

Here files is the name you give the server, and everything after -- is how it launches. Many servers ship as npm packages, so npx pulls them on demand the first time they are needed. You do not install anything by hand.

Listing and removing

See what is configured with:

bash
claude mcp list

Remove one by name when you no longer need it:

bash
claude mcp remove files

Where the config lives

When you add a server, Claude writes it to .mcp.json in the current project (or to your user config, depending on scope). That file is just JSON, so you can read it, commit the project-scoped one to share with your team, or edit it by hand. The next time you start Claude in that project, the servers are available again.


Your lab setup

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