Do these configs run anything?

No. The builder only writes the snippet. You paste it into your client’s config file, then restart the client so it loads the server.

What is a local versus a remote server?

A local server runs on your machine with npx or uvx. A remote server is hosted, and you connect over HTTP with OAuth or a token. The snippet changes to match.

A server needs a key or a login. Where does it go?

A token goes in the env block or a header, shown with a placeholder. An OAuth server prompts you to sign in on first run. Keep tokens out of version control.

MCP config builder

Claude Code

Add it in one line

claude mcp add filesystem -- npx -y @modelcontextprotocol/server-filesystem /path/to/allowed/dir

Add -e KEY=value for env vars. Scope: the default is this project only; add --scope project to share it in a committed .mcp.json, or --scope user for all your projects.

Or edit .mcp.json

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/path/to/allowed/dir"
      ]
    }
  }
}

Config file: .mcp.json in your repo root.

Cursor .cursor/mcp.json

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/path/to/allowed/dir"
      ]
    }
  }
}

Config file: ~/.cursor/mcp.json (all projects) or .cursor/mcp.json (one project).

Codex ~/.codex/config.toml

[mcp_servers.filesystem]
command = "npx"
args = ["-y", "@modelcontextprotocol/server-filesystem", "/path/to/allowed/dir"]

Using your first remote server in Codex? Add experimental_use_rmcp_client = true under [features] in the same file.

Config file: ~/.codex/config.toml.

Claude Desktop claude_desktop_config.json

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/path/to/allowed/dir"
      ]
    }
  }
}

Claude Desktop reaches a remote server through the mcp-remote bridge shown above, or you can add it from Settings, Connectors.

Config file on macOS: ~/Library/Application Support/Claude/claude_desktop_config.json.

How it works

Every client stores MCP servers in a small config file. Pick a server and the snippets for all four clients update together. Local servers use a command; remote servers use a URL. Claude Code, Cursor and Claude Desktop use JSON; Codex uses TOML.

Pick the server above.
Copy the snippet for your client and open its config file (the path is under each).
Merge it into your existing servers, replacing any placeholder path, key or project ref.
Restart the client. The tools load at the start of the next session.

The servers and endpoints were checked on 2026-10-23 against each one’s own docs. For connecting a board over MCP, see connect Claude Code.