Agent door

Connect ChatGPT

Add Yellowhead to ChatGPT as a custom server and sign in. Then mention @Yellowhead in a chat to read your Diagnostics and reports, or start a new Diagnostic.

ChatGPT connects to your account through the agent door, a Model Context Protocol (MCP) server at https://api.yellowhead.digital/mcp. You add it to ChatGPT yourself as a custom MCP server and sign in with your Yellowhead Digital account. On the Yellowhead side it works on every plan, Free included.

Before you start

You need a Yellowhead Digital account. You sign in to it during setup.
Whether you can add a custom MCP server depends on your ChatGPT plan, and OpenAI controls it. It may not be available on every plan, and on some plans a custom server may be limited in what it can do. On a ChatGPT workspace, the workspace's own policies apply too. Check OpenAI's help pages for your plan.

Add the MCP server

In ChatGPT's settings, open the apps or plugins area (OpenAI's developer guide points to chatgpt.com/plugins) and choose Add custom MCP server. Do not choose Create plugin or Upload plugin archive: those are for building a plugin of your own.
Name it Yellowhead. A description is optional.
Enter the URL https://api.yellowhead.digital/mcp.
For authentication, choose OAuth.
ChatGPT shows a warning about custom MCP servers. Read it, confirm, and create the server. If ChatGPT then asks you to install it, install it.

ChatGPT sends you to app.yellowhead.digital/oauth/authorize, Yellowhead Digital's consent page. If you are not signed in, sign in there first. The page then shows:

Who is asking. The heading names the app and, under it, the verified web address that sent the request. If the app registered itself automatically, the page says so and that it cannot verify who made it.
Where you go back to once you decide.
Which account it can read. Your Personal account and any Team accounts you belong to. Pick one. An account that cannot be connected is greyed out, with the reason.
What it will be able to do in the account you picked. The list follows that account's Yellowhead plan, so it can change when you pick a different account. You see it before you approve.
A note that what it reads is sent to the app and kept under the app's own policies.

Choose Allow to connect, or Deny. Either way you go back to ChatGPT.

What the list can include

On the consent page	Which accounts
Read the Diagnostics and reports in this account	Every plan
Read its action items	Pro, Enterprise, any Agency plan (Consultant, Studio or Firm) and custom plans
See this account's plan usage	Every plan
Read published Strategic Assessments	Every plan
Start a Diagnostic using one of your account's included monthly Diagnostics	Every plan. On a plan with workspaces, the line adds that it can file the run in one of your workspaces. On an Agency plan (Consultant, Studio or Firm) or a custom plan, it adds that it can also create a new prospect or client workspace for the business when you ask for one.
See the Portfolio: your client workspaces and how their scores moved	Team accounts on an Agency plan, Business Enterprise or a custom plan
Read published Infrastructure Audits	Every plan
Read its Citation, Crawlability and Accessibility Scans	Every plan

A connection can do only what you can do in the account it is connected to. Creating a prospect or client workspace needs you to be an owner or admin of the team account. A connection made by signing in holds no action-item write capability: it cannot change, comment on or close an action item. See Capabilities for the detail.

Mention @Yellowhead in a chat

ChatGPT can answer from its own knowledge instead of calling a connected server. Start a new conversation, type @ in the prompt box and pick Yellowhead, or write @Yellowhead at the start of your question, for example "@Yellowhead what Diagnostic reports do I have?". If you gave the server another name, use that name.

Starting a Diagnostic

When you ask ChatGPT to start a Diagnostic, the first step is a preview, and it starts nothing: the website, the business name, the self-ratings, what the run will be recorded as and where it will be filed, and which of your included monthly Diagnostics it uses. The run starts only when ChatGPT confirms that preview, and any change needs a new preview. ChatGPT may confirm without asking you again, so if you want to approve each run, ask it to show you the preview and wait for your go-ahead. A Diagnostic uses only your account's included monthly Diagnostics. When none are left, nothing is charged, and ChatGPT is told the reset date. One person can also start only so many from an assistant in a day.

You can say what the Diagnostic is for, with the same choices as the app: your own business, a client, a competitor or research, and, on an Agency plan, a prospect (an owner or admin of the team account can have a new prospect created for it). A competitor or research run of a website none of your workspaces holds is filed in no workspace, and no workspace is created for it. A website one of your client or brand workspaces already holds is filed in that workspace, as it is in the app.

A Diagnostic takes 5 to 10 minutes, and you also get an email when it completes. Ask "@Yellowhead is my Diagnostic ready yet?" to check on it.

Manage or remove the connection

Your own connections. In the Yellowhead Digital app, open Settings › AI assistants (app.yellowhead.digital/dashboard/settings/ai-assistants). It lists each assistant you have connected, the account it is connected to, and what it can do. Remove cuts off its access within about a minute. To use it again, connect it again from ChatGPT.
Owners and admins of a team account see everyone's connections to that account under Access › AI assistants, and can remove any of them. The setting Members may connect AI assistants is on by default. Turning it off ends members' current connections and stops new ones. Owners and admins keep theirs.

Troubleshooting

ChatGPT answers from memory instead of from Yellowhead: Mention the server by name: start your question with @Yellowhead. See Mention @Yellowhead in a chat.
A "not in plan" refusal: Your Yellowhead plan does not include that feature, so nothing was read. Reading action items needs Pro or above, for example. The plans page says which plan includes what.
"This connection was set up before that was available to this account": The account gained the feature, or Yellowhead switched it on, after you connected, for example after an upgrade. Reading Citation, Crawlability and Accessibility Scans is one such feature: a connection made before Yellowhead added scan reads on 2026-11-06 gets this message for them. Connect Yellowhead again in ChatGPT; the new connection gets what the account can do now.
"A connection made by signing in from an assistant cannot do that on any plan": The request needs access a sign-in connection never has, such as changing an action item. Do it in the Yellowhead Digital app instead.
"The sign-in for this connection has expired or was revoked": The connection was removed, or went unused for 30 days, or, for a member of a team account, ended when an owner or admin turned off Members may connect AI assistants. Connect it again from ChatGPT. While that setting is off, a member needs an owner or admin to turn it back on first.
An account is greyed out on the consent page: The reason is shown next to it: the team account is paused, you have client access there (which cannot be connected to an AI assistant yet), or its owners and admins have turned off AI assistants for members.
"You already have 10 AI connections to this account": One person can have up to 10 connections to an account. Remove one you no longer use at Settings › AI assistants, then try again. A connection that goes unused for 30 days also frees its place on its own.
You cannot find Add custom MCP server: Your ChatGPT plan or workspace may not offer it. Some ChatGPT accounts show it only once Developer Mode is switched on in ChatGPT's settings. OpenAI decides this, not Yellowhead; check OpenAI's help pages for your plan.