How to Add an MCP Server to ChatGPT

Alek Perak

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21 hours ago

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Two ways to add an MCP server to ChatGPT, which plans allow it, how sign-in works, and fixes for common errors

By Alek Perak, founder of TokenRip

A custom MCP server can appear connected in ChatGPT while a required write tool remains unavailable. Check the whole path: discovery, sign-in, a useful read and an approved test write. The setup routes below explain where to start; the final test tells you whether the connection supports your workflow.

Method 1: Add an MCP server to ChatGPT with Plugins

The Plugins flow is the easiest path because it doesn’t need Developer mode (OpenAI help (https://help.openai.com/en/articles/12584461-connecting-custom-mcp-servers-in-chatgpt)).

1. Open Plugins in ChatGPT on the web.
2. Select +, then Add custom MCP server.
3. Enter a name and an optional description.
4. Under Connection, enter the server’s public HTTPS endpoint. For a private server, choose Tunnel.
5. Set up sign-in, read the risk warning and check I understand and want to continue.
6. Select Create as a plugin, review the tools ChatGPT found, and install.
7. Open a new chat, type @ and pick the plugin. Test one read and one write.

ChatGPT asks you to confirm write actions.

Method 2: Use Developer mode

Developer mode gives “full Model Context Protocol (MCP) client support for all tools, both read and write” (OpenAI developer docs (https://developers.openai.com/api/docs/guides/developer-mode)). OpenAI also calls it “powerful but dangerous.”

1. Go to Settings > Apps > Advanced settings and turn on Developer mode.
2. Click Create app and enter the server URL.
3. The app shows up under Drafts. In a chat, pick Developer mode from the + menu and select it.

If neither setup route appears, check your account’s plan and workspace permissions against the linked official documentation.

Which ChatGPT plans can add MCP servers?

OpenAI’s two pages give different answers, so check yours:

• Developer docs: Developer mode is “Available to Pro, Plus, Business, Enterprise, and Education accounts on the web.”
• Help center: “Full MCP is only available to Business and Enterprise/Edu users, currently.” It lists Pro as read and fetch only.

What to do:

• On Business, Enterprise or Edu, ask your admin. Admins create and publish servers or grant permission.
• On Plus or Pro, connect the server, then test whether its write tools run.
• Free and Go aren’t listed in either page.

How does sign-in work?

ChatGPT supports OAuth, no sign-in, or a mix. Neither OpenAI page shows a field for pasting an API key.

• OAuth: static client credentials if you have them. Otherwise ChatGPT uses Client ID Metadata Documents (CIMD) or Dynamic Client Registration (DCR), if the server supports them.
• Mixed: tools are listed without sign-in, and each tool uses OAuth or none.
• Staying signed in: the server must include the offline_access scope. Without it, “ChatGPT may lose access after the original authorization expires.”

Any tool without a readOnlyHint annotation counts as a write, so ChatGPT asks before running it.

Can I add a local MCP server to ChatGPT?

Not directly on the web. ChatGPT can’t reach a server on your laptop or a private network. OpenAI’s answer is Secure MCP Tunnel (OpenAI guide (https://developers.openai.com/api/docs/guides/secure-mcp-tunnels)):

1. Create a tunnel in the OpenAI Platform’s tunnel settings.
2. Run tunnel-client inside your network. It opens an outbound HTTPS connection, so no inbound ports are needed.
3. When you add the server, choose Tunnel under Connection.

The ChatGPT desktop app is different. Its MCP settings are for Codex: Settings > MCP servers > Add server, with STDIO or Streamable HTTP. From a terminal, codex mcp add <name> — url <url> does the same.

How to fix common ChatGPT MCP errors

• “Create app” is missing. It only shows in Developer mode. Turn that on, or use Plugins.
• No tools appear. On Business and Enterprise, an admin can refresh the tool list in workspace app settings.
• ChatGPT keeps asking you to sign in. Check whether the server grants offline_access and refresh tokens. Repeated sign-in can also have other authentication causes; inspect the actual error before changing the configuration.
• A local server won’t connect. The web can’t reach it. Use Secure MCP Tunnel.

Why connect a shared workspace?

Most people add one service to ChatGPT. If ChatGPT is one of several agents on the same work, the server can be the place they all share. Then a deck built in ChatGPT reflects what your other agents did, without pasted summaries.

Disclosure: I’m the founder of TokenRip, a shared workspace with an MCP endpoint at api.tokenrip.com/mcp. Its OAuth server supports CIMD and PKCE. One caveat from our FAQ: ChatGPT can add TokenRip as a custom connector on plans that allow custom connectors (Developer Mode), and we haven’t finished our own end-to-end run in ChatGPT yet. Check that write tools work on your plan before you rely on them. Details at https://tokenrip.com.

Keep a connection receipt you can repeat

Use a disposable record and write down the account, server URL, date, discovered tool and observed result. Test a read before a write. After an approved write, reopen the target record outside the chat and compare its value. If it fails, keep the exact error and distinguish an unavailable tool from a failed login or denied permission. That short receipt is more useful for troubleshooting than “MCP does not work.”