Fathym
Menu
fAIOpenXThe LoopHolonicAboutDocsBlogLog in to OpenX
Docs menu

MCP: ChatGPT

ChatGPT on the web can add a remote MCP server of your own. OpenAI lists OAuth sign-in as an authentication choice, so you sign in with OpenX in the browser and there is no key to store.

Steps and button names below are from OpenAI's developer documentation, checked 2026-10-13. Menu labels are as of that date and may change; OpenAI's pages say workspace permissions and security settings apply, so a workspace admin may need to allow it first.

What is not confirmed

  • OpenAI's help center article on developer mode and MCP apps could not be fetched when this page was checked (it returned HTTP 403), and the two developer pages used here do not list which ChatGPT plans can add a custom MCP server. Check your plan against OpenAI's help center before you start.
  • The names of the screens that enable the feature have differed between OpenAI's pages. This page gives only the steps the developer pages agree on.

The address

https://openx.fathym.com/ox-api/mcp

OpenAI asks for a public HTTPS address that supports Streamable HTTP, typically ending in /mcp. The OpenX address does. To pin the connection to one workspace, use <origin>/ox-api/mcp/w/<workspace id>.

Connect

  1. Go to chatgpt.com/plugins.
  2. Select the plus button, then Add custom MCP server.
  3. Enter a name, such as OpenX, and optionally a description.
  4. Under Connection, enter the server address above.
  5. Configure authentication: choose OAuth.
  6. Review the risk warning and select I understand and want to continue.
  7. Select Create as a plugin.
  8. Install the plugin. When ChatGPT sends you to the OpenX sign-in, sign in, pick the workspace, and tick the rights to share with the connection.

Use it

Open a new chat, type @ in the prompt box, and select the OpenX plugin. Then ask: "What were the average signups per hour today?" ChatGPT calls call_api against your saved source of truth. To build, it proposes with manage_proposals, and you accept in the portal.

If the tools change

After the OpenX tools change, open the connection at chatgpt.com/plugins and select Refresh, then start a new conversation.

A pasted key

OpenAI's developer pages list OAuth, no authentication, and a mixed mode as the choices. They do not list a pasted key or header, so this page gives none. Use the browser sign-in.

On this page