How to add an MCP server to Claude Desktop, step by step

Claude Desktop can use tools that run on your own computer: a folder of files, a database, an app such as a bookmark library. Each of those tools arrives through an MCP server, a small program Claude starts and talks to. Adding one takes a couple of minutes, and nearly every problem people hit comes down to the same four or five mistakes in one file. Some Mac apps, such as Muse, a $29 visual library for saved pictures, links and notes, now include their own MCP server, so there is nothing extra to install.

This guide covers both routes Claude Desktop offers on a Mac, the config file most servers still need, and what to check when a server refuses to appear. The steps follow the official Model Context Protocol guide and Anthropic's own help pages.

What do you need before you start?

You need three things. First, Claude Desktop itself, the app from claude.ai/download, on its latest version: choose Check for Updates from the Claude menu. Second, the server you want to add, which usually means one line of setup from its maker. Third, for many community servers, Node.js, because they run through a helper called npx. Type node --version in Terminal; if you get a version number back, you are set.

One thing trips people up before they begin. Local MCP servers only work in the desktop app. Claude in a web browser and the Claude iPhone app cannot start programs on your Mac, so a server you add here will not show up there.

Two ways in: Extensions or the config file

Claude Desktop now has two routes. The simpler one is Settings > Extensions, where you can browse a directory of reviewed extensions and install one with a click, or install a .mcpb file a developer gives you. An extension bundles the server and everything it needs, so there is no JSON to edit.

Most servers are not packaged that way yet. For those, you use the config file: a small text file called claude_desktop_config.json that lists every server Claude should start. That is the route the rest of this guide covers.

How do I add an MCP server to Claude Desktop?

1. Open the right Settings. Click the Claude menu in your Mac's menu bar and choose Settings. This is the app's own settings window, not the account settings inside a chat.
2. Go to Developer. Choose the Developer tab in the sidebar, then click Edit Config. Claude creates the file if it does not exist yet, then opens it.
3. Quit Claude completely. Press Command-Q rather than closing the window. Claude can rewrite this file while it is running, so edit it with Claude closed. The official guide puts the rule plainly: "completely quit Claude Desktop and restart it."
4. Edit the file as plain text. It lives at ~/Library/Application Support/Claude/claude_desktop_config.json. In TextEdit, choose Format > Make Plain Text first.
5. Paste the server's setup and save. If the file is empty, paste the whole block the server's maker gives you. If it already lists servers, add the new one inside the existing mcpServers section, as shown below.
6. Reopen Claude and check. Claude reads this file when it starts. Click the button in the bottom-left of the chat box (it reads "Add files, connectors, and more"), then Connectors, then Manage connectors. Your server should be in the list with its tools.

Here is the example the official guide uses, the reference filesystem server, which gives Claude access to one folder. Replace username with your own Mac username.

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/Users/username/Desktop"
      ]
    }
  }
}

What does the config file look like with two servers?

This is where most setups break. There is one mcpServers section, and every server sits inside it, separated by a comma. People often paste a second complete block underneath the first, which gives the file two top-level sections and makes it invalid. The right shape looks like this:

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/Users/username/Desktop"]
    },
    "muse": {
      "command": "/Applications/Muse.app/Contents/MacOS/muse-mcp"
    }
  }
}

The name before each colon (filesystem, muse) is yours to choose. It is only the label Claude shows you.

Why is my MCP server not showing up in Claude Desktop?

Work down this list in order. Each step rules out one cause.

1. Quit and reopen properly. A closed window leaves Claude running with the old settings. Use Command-Q.
2. Check the file's shape. One mcpServers section, commas between servers, straight quotes, every bracket closed.
3. Use full paths. Paths must start from the top of your disk, such as /Users/username/Desktop, never a shortened or relative one.
4. Read the logs. Claude writes MCP logs to ~/Library/Logs/Claude. The file mcp.log records connection failures, and each server gets its own mcp-server-NAME.log. In Terminal, tail -n 20 -f ~/Library/Logs/Claude/mcp*.log shows the latest lines.
5. Run the command yourself. Copy the server's command into Terminal. If it errors there, it will error inside Claude too, and Terminal usually says why, such as npx not being installed.

If Claude can see a server but its tools fail when used, check the server's own log first, then restart Claude once more.

A worked example: connecting a Mac app

Some Mac apps now include their own MCP server, so there is nothing to install and no Node.js to worry about. Muse is one of them, from version 1.0.40. In Muse, open Settings > Intelligence, turn on Allow AI Apps under MCP Server, and click Copy Setup. It copies this, pointing at a helper inside the app:

{
  "mcpServers": {
    "muse": {
      "command": "/Applications/Muse.app/Contents/MacOS/muse-mcp"
    }
  }
}

Paste it into the config file following the steps above, reopen Claude, and it can search your saved pictures, links and notes, look at images, and file things into collections. Anything it removes goes to Muse's Trash, which only you can empty. The full walkthrough, with the questions worth asking, is on the Connect AI Apps guide.

Whatever server you add, the pattern is the same: one entry in one file, a full restart, and a quick look under Connectors to confirm it arrived.