What Is an MCP Config? A Complete Structure Guide

An MCP config is a JSON file that tells an AI client which Model Context Protocol (MCP) servers to start and how to reach them. Every config wraps server definitions in a top-level mcpServers object, except Zed, which uses an mcp object.

The mcpServers wrapper

The outer object is usually mcpServers. Inside it, each key is a server name you choose, and the value is a server object. Server names must be unique within the file.

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-github"]
    },
    "weather": {
      "url": "https://weather.example.com/mcp",
      "transport": "http"
    }
  }
}

Server object fields

A server object contains the connection details. Either command or url is required; everything else depends on the transport and client.

command

The executable to launch for stdio servers, such as npx or python3.

args

An array of arguments passed to command. Include -y for npx so it does not wait for confirmation.

env

An object of environment variable key-value pairs, both strings. Used for tokens and settings.

url

The remote endpoint for Streamable HTTP or SSE servers. Must include http:// or https://.

transport

Required for remote servers: http for Streamable HTTP or sse for legacy SSE.

enabled / disabled

Optional booleans used by some clients, such as Cline, to turn a server on or off without deleting it.

autoApprove

A Cline-specific array of operation names that can run without asking for permission each time.

headers

Optional object of HTTP headers sent with remote transport requests, typically for authentication.

The env object

The env object holds environment variables as string key-value pairs. Values are stored in plaintext, so keep the config file out of git and screenshots. If a server needs a token, put it here, not in args.

"env": {
  "GITHUB_TOKEN": "ghp_xxxxxxxxxxxxxxxxxxxx",
  "OPENWEATHER_API_KEY": "your-key-here"
}

Transports in a config

stdio servers use command and args; remote servers use url and transport. See the full transport comparison for details.

Valid vs invalid example

A single trailing comma after the last array item makes the whole file invalid JSON. The fixed version removes it.

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-github",
      ]
    }
  }
}

{
  "mcpServers": {
    "github": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-github"
      ]
    }
  }
}

Client-specific wrappers

Most clients read mcpServers. Zed is the main exception: it reads an mcp object inside its settings.json. VS Code stores per-workspace servers in .vscode/mcp.json and can also put user-level servers in settings.json under mcp.servers.

Frequently asked questions

Try the MCP Config Generator to produce a valid config, or compare stdio, SSE, and Streamable HTTP.