GUIDE · UPDATED 22 OCTOBER 2026

How to add an MCP server to Claude, ChatGPT, Cursor and Codex.

Q: Where is Cursor’s MCP config file?

~/.cursor/mcp.json for every project, or .cursor/mcp.json inside one project. Both use the same mcpServers format.

Q: How do I add an MCP server in Claude Code?

For a remote server, run claude mcp add --transport http NAME URL, then type /mcp in Claude Code and choose Authenticate. For a local one, run claude mcp add NAME -- COMMAND ARGS.

An MCP server gives your AI assistant tools from another product, through the open Model Context Protocol. There are two kinds. A remote server is a web address your assistant connects to, usually with an OAuth sign-in. A local server is a command that runs on your own computer. Here is how to add each kind in the four assistants people use most.

Assistant	Remote server (URL)	Local server (command)	Where the setup lives
Claude (web and desktop)	Settings → Connectors → Add custom connector	Claude Desktop only, in its config file	Your Claude account; `claude_desktop_config.json`
Claude Code	`claude mcp add --transport http`	`claude mcp add NAME -- COMMAND`	Per project or per user
ChatGPT	Developer mode, where your plan allows it	Not supported	Your ChatGPT account or workspace
Cursor	`"url"` in mcp.json	`"command"` in mcp.json	`~/.cursor/mcp.json` or `.cursor/mcp.json`
Codex	`codex mcp add NAME --url URL`	`codex mcp add NAME -- COMMAND`	`~/.codex/config.toml`

Claude

In Claude, open Settings → Connectors → Add custom connector. Availability depends on your plan.
Enter the server’s URL, then sign in and approve when Claude opens the provider’s page.
Turn the connector on in a conversation from the tools menu.

For a local server in Claude Desktop, open Settings → Developer → Edit Config and add it under mcpServers with its command and args, then restart Claude. See Claude’s connector guide.

Claude Code

Remote: claude mcp add --transport http NAME URL. Local: claude mcp add NAME -- COMMAND ARGS.
Add --scope user to use it in every project, or --scope project to share it with your team through the repository.
Start Claude Code, type /mcp and choose Authenticate for servers that need a sign-in.

ChatGPT

Enable developer mode in ChatGPT’s settings, where your plan or workspace administrator allows it.
Create a connection with the server’s URL and its authentication, usually OAuth.
Sign in when asked, then turn the connection on in your conversation.

ChatGPT runs in OpenAI’s cloud, so it can only reach remote servers. See OpenAI’s developer-mode guide.

Cursor

Open ~/.cursor/mcp.json, for every project, or .cursor/mcp.json in one project.
Remote: {"mcpServers":{"NAME":{"url":"URL"}}}. Local: {"mcpServers":{"NAME":{"command":"npx","args":["PACKAGE"]}}}.
In Cursor’s MCP settings, click Connect next to the server and sign in if asked.

See Cursor’s MCP guide.

Codex

Remote: codex mcp add NAME --url URL, then codex mcp login NAME to sign in. Local: codex mcp add NAME -- COMMAND ARGS.
The setup is saved in ~/.codex/config.toml and shared by the Codex CLI, IDE extension and desktop app.

See OpenAI’s Codex MCP guide.

If the tools don’t appear

Restart the assistant or reconnect the server; most clients read the list of tools when they connect.
If sign-in fails, remove the server and add it again so the OAuth flow starts fresh.
If the assistant has too many tools to choose well, turn off the servers you are not using in this conversation.

Try it with an MCP server for SEO and AI visibility

Search is changing: your buyers ask AI assistants as well as Google. Organiq’s remote MCP server brings that research into your assistant. Connect https://organiq.tech/mcp and ask Claude “which buyer questions do AI assistants answer without naming us, and who do they name instead?”, then have Codex or Cursor prepare the fix as a pull request. Reading your results is free; new research is quoted before it runs.

Set up the Organiq MCP server →

Common questions

What is an MCP server?

A program that offers tools to an AI assistant through the Model Context Protocol, an open standard. A remote server is a web address your assistant connects to, usually with OAuth sign-in; a local server is a command that runs on your own computer.

Can ChatGPT use a local MCP server?

No. ChatGPT runs in OpenAI’s cloud, so it connects only to remote servers it can reach over the internet. Claude Desktop, Claude Code, Cursor and Codex can run local servers too.

Where is Cursor’s MCP config file?

~/.cursor/mcp.json for every project, or .cursor/mcp.json inside one project. Both use the same mcpServers format.

How do I add an MCP server in Claude Code?

For a remote server, run claude mcp add --transport http NAME URL, then type /mcp in Claude Code and choose Authenticate. For a local one, run claude mcp add NAME -- COMMAND ARGS.

Are MCP servers safe?

Add only servers from providers you trust. A server can read what your assistant sends it, and its tool descriptions and answers reach your assistant. Prefer OAuth over pasting API keys, review what each tool can change, and remove servers you no longer use.