In Claude Desktop's `` config file, MCP servers are registered under the `` key. A stdio server entry uses the `` and `` fields to specify the executable and its arguments. A remote Streamable HTTP server uses a `` field instead.
Claude Desktop discovers MCP servers from a single file named `claude_desktop_config.json`. You edit it through Settings, and it lives in the app's support directory on your machine.
Inside that file, every server you want to use goes under one top-level key: `mcpServers`. Each entry is named by you, and its value is an object describing how to reach that server.
For a **stdio server** (a local program), you give two fields. The `command` field names the executable to run, like `npx` or `python`. The `args` field is an array of arguments passed to that command, such as the package name or a script path.
For a remote server, you do not launch anything locally. Instead you give a `url` field pointing at the server's Streamable HTTP endpoint. Claude Desktop connects over the network rather than spawning a process. That single distinction, run a command versus hit a URL, is the whole answer.
Claude Desktop reads one JSON file at startup: `claude_desktop_config.json`. It sits in the per-user application support directory, and you usually edit it through the Settings dialog.
The file has one top-level key that matters here: `mcpServers`. It maps a server name you choose to a connection spec. That spec branches on transport.
For a stdio server, Claude Desktop launches a local subprocess and talks JSON-RPC over its standard input and output. You specify `command`, the executable such as `npx`, and `args`, an array passed to it such as the server package. An optional `env` object injects environment variables, which is where secrets like API keys belong.
For a remote server using Streamable HTTP, there is no local process to spawn. You supply a `url` field pointing at the server's HTTP endpoint, and Claude Desktop connects over the network instead. So the shape of an entry tells you the transport. The pair command plus args means stdio, while url means remote HTTP. Get those field names right and the host wires the discovered tools into the model automatically.
Quick reference
TL;DR
Claude Desktop reads claude_desktop_config.json; each server lives under mcpServers, with command plus args for a stdio launch, or a url field for a remote Streamable HTTP server.
Think of the config file as a contacts list for tools. Claude Desktop reads one JSON file at startup to learn which tool servers exist. Under a single mcpServers heading, each server gets a name and instructions for reaching it. A local server is like a program on your machine, so you give the command to run it plus the args, the arguments handed to that command, exactly as you would type them in a terminal. A remote server already runs somewhere on the network, so instead of launching anything you just hand over its url. Same address book, two ways to write a contact: dial a local number, or point at a web address.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example.
Configuring Claude Code or another host rather than Claude Desktop Claude Code reads its own config location and CLI flags; the file name and edit flow differ from the desktop app.
A purely remote server that exposes only an HTTP endpoint command and args spawn a local process and do nothing useful here; the entry needs a url field instead.
Injecting a secret you do not want sitting in plaintext config Both args and env land in a readable JSON file; for stronger handling reach for an OS keychain or a remote server with OAuth.
Quick scan · 2–4 min
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5 min: name the file and the mcpServers key, walk command plus args for the stdio launch, contrast url for remote Streamable HTTP, then cover env for secrets and the restart requirement.