Connect ChatGPT to the Functionize MCP Server

ChatGPT can connect to the Functionize MCP server as a custom app. The setup is different from the other clients in this section: it is done entirely in the ChatGPT web interface, it requires a workspace plan, and it is controlled by your ChatGPT administrator rather than by you.

This guide reflects ChatGPT's developer mode as documented by OpenAI. Because that feature is still evolving, check OpenAI's own help article if a menu has moved.

What you need first

• A ChatGPT Business, Enterprise or Edu workspace. Custom MCP apps and developer mode are workspace features on ChatGPT web. They are not available on personal plans.
• Administrator involvement. Only admins and owners can enable developer mode and publish an app. On Enterprise and Edu, an admin can grant developer access to specific people through role-based access control.
• A Functionize account, which you will sign in with during setup.

There is nothing to install. ChatGPT talks to remote HTTPS servers only, so no bridge and no Node.js are involved.

Step 1 — Turn on developer mode

Where this lives depends on your plan.

Business — an admin or owner enables it in Workspace Settings → Permissions & Roles → Connected Data, using the developer mode / create custom MCP connectors toggle. Each admin enables it for themselves; it is not applied to everyone at once.

Enterprise and Edu — admins and owners enable it from Settings → Apps → Advanced Settings. Admins can use role-based access control to grant developer mode to specific members, who then toggle it on for themselves in the same place.

Step 2 — Create the app

Admins go to Workspace Settings → Apps → Create. Authorised users go to their own Settings → Apps → Create.

Fill in the details:

Then click Scan Tools. ChatGPT connects to the server and reads the available tools. You will be prompted to complete the Functionize sign-in during this step — use the same account you use for Functionize Studio, or your organisation's SSO. Wait for the scan to finish, then click Create.

The app now appears as a draft under Workspace Settings → Apps → Drafts, and in your own Settings → Apps → Enabled Apps with a Dev label.

Step 3 — Test it

Open a new chat, select the draft app from the tools menu or mention it in your prompt, and ask it to list your Functionize agent sessions. ChatGPT asks you to confirm actions depending on the app's permissions, so expect a prompt before anything is written.

Step 4 — Publish it, if you want others to use it

Only admins and owners can publish. Go to Workspace Settings → Apps → Drafts and click Publish. Review the safety warnings, particularly around write actions. Once published, the app appears in the workspace's approved connectors and in members' Apps settings with a custom label.

On Enterprise and Edu, admins can use Configure Actions to choose exactly which tools the app may use, and Configure Access to limit it to particular groups. Both can be revisited afterwards from the app's Action control menu.

A note on staying connected

OpenAI warns that if an MCP server's OAuth provider does not issue refresh tokens, ChatGPT can lose access once the original authorisation expires, forcing people to sign in repeatedly.

This is not a problem with the Functionize server. We advertise offline_access in our OAuth metadata and support the refresh_token grant type, which is exactly what that requirement asks for. You can verify it yourself:

https://mcp.functionize.com/.well-known/oauth-authorization-server

Look for offline_access under scopes_supported and refresh_token under grant_types_supported.

Limitations worth knowing before you start

• ChatGPT web only. Custom apps are configured and used on the web client.
• No local servers. ChatGPT connects to remote HTTPS endpoints only. That suits our hosted server, but it means the stdio @functionize/mcp package is not an option here.
• Business plans cannot edit a published app. To change tools or metadata after publishing, recreate and republish it. Enterprise and Edu have finer controls, including refreshing the action list in place.
• Updates are not automatic. If we add tools to the server, an admin needs to use Refresh to pick them up. New actions arrive disabled by default.
• Team pinning is not available here. ChatGPT's app configuration does not expose custom request headers, so the connection acts as your active Functionize team. If you need a specific team, use a client that supports the X-Functionize-Team-Id header — see Connect Any MCP Client.

If something goes wrong

If the tool scan fails, check that you entered the URL exactly, including the /mcp path, and that you completed the sign-in prompt rather than closing it.

If the app connects but does not appear in a chat, confirm it is enabled in Settings → Apps and that you have selected it for that message — app selection applies per message, not for a whole conversation.

For anything else, see Troubleshooting the Functionize MCP Connection, or raise a ticket with your account email and the point at which it stops.