Connect ChatGPT to StackJack

ChatGPT can call your MSP tools through StackJack using MCP (Model Context Protocol — the open standard AI tools use to call external tools). You connect it with OAuth sign-in: paste one URL, sign in with your StackJack account, and there are no credentials to copy.

Prerequisites

• A paid ChatGPT plan — Plus, Pro, Business, Enterprise, or Edu. Free accounts do not see the Developer mode toggle.
• On a Business workspace, only workspace admins/owners can enable and use Developer mode — OpenAI does not let individual members be granted it. On Enterprise or Edu, admins grant Developer mode access per person via role-based access control, and a granted member can then toggle it themselves. The admin-side toggle lives under Workspace Settings → Permissions & Roles → Connected Data (Developer mode / Create custom MCP connectors).
• ChatGPT on the web in a desktop browser (Developer mode / custom connectors are web-only — the mobile and desktop apps don't offer them).
• A StackJack account that is a member of your workspace. Any team member can connect — no admin-created credentials needed.
• Your StackJack MCP endpoint URL. Copy it from the MCP Setup page in the portal — that card shows the address for your workspace's region. The examples in this guide use the US address, https://mcp.stackjack.io/mcp; other regions have their own hostname. See Your region and your endpoint.

Connect with sign-in (recommended)

The one thing to know before you start: the StackJack sign-in happens inside the create dialog, at the moment ChatGPT reaches out to the server to read its tool list — it is not a popup that arrives after the connector is created. If you finish the dialog without ever seeing a StackJack sign-in, that step never ran, and the half-made connector will not work no matter how long you wait.

1. Turn on Developer mode. Depending on which ChatGPT build your account is on, the toggle is under Settings → Apps → Advanced settings or under Settings → Security and login — OpenAI currently documents both locations, so check both.
2. Create the connector from the developer-mode surface your build gives you: the Create button on the Apps screen, or the + button at chatgpt.com/plugins (the + button only creates developer-mode apps once Developer mode is already on).
3. In the dialog, name the app (for example "StackJack") and enter the MCP endpoint URL — https://mcp.stackjack.io/mcp, including the /mcp on the end.
4. Set Authentication to OAuth. Do not leave it on No authentication — the connector will not be able to reach StackJack. Leave Client ID and Client Secret blank; ChatGPT discovers StackJack's OAuth endpoints automatically.
5. Now the key part: before you leave the dialog, trigger the step that makes ChatGPT read the server's tools — depending on your build that is the Create action itself, or a separate scan/validate step in the same dialog. That action opens the StackJack sign-in (same email, password, and MFA as the StackJack Portal). Complete the sign-in and let the tool list finish loading before you finish creating the app.
6. To use the connector in a conversation, open the composer's Developer Mode menu and turn the StackJack connector on for that chat — it is off by default in every new chat.

If you see a consent screen

ChatGPT supports both ways AI products identify themselves to StackJack — per-install registration and a shared-app identity (CIMD). If ChatGPT connects as a shared app, StackJack shows a branded consent screen after sign-in with a "Verify before you approve" panel listing the app's identity (client_id) URL, where the authorization will be sent, and your workspace name. Choose Allow access to finish connecting. Shared-app connections appear as Connected apps that admins manage per member on the Team page; per-install connections appear as read-only AI sessions (in your own MCP Setup self-view, and per member on the Team page for admins) instead. Either way, the connection works the same in ChatGPT. See How AI tools authenticate for the full picture.

Manual credentials (optional)

If you prefer static credentials over signing in, an owner, co-owner, or Administrator can create an MCP client on the MCP Setup page, and you can enter the Client ID and Secret in the ChatGPT app's Advanced settings instead. See Managing MCP credentials. For most people, sign-in is simpler and safer.

Tool limits

ChatGPT does not publish a hard cap on MCP tool counts, but very large tool lists cost context and make tool choice less reliable. Depending on your connectors and plan, StackJack can expose hundreds of tools. If your admin has restricted your tool grants, or you connect through a restricted client, ChatGPT only sees the allowed subset. For strategies on focused tool sets, see Choosing tools for each client.

If a large catalog slows ChatGPT down, switch StackJack to compact catalog mode so it serves a small tool list and discovers the rest on demand. ChatGPT rejects query-string server URLs as unsafe, so don't use ?tools=. Instead, point your connector at https://compact.stackjack.io/mcp — a dedicated address that serves the compact catalog to every connection, with nothing to enable first. As an alternative to that address, set your connection to Compact in the My AI tool catalog card on the Connectors page, or have an admin set the organization default — for ChatGPT's sign-in connection, the per-client setting on MCP Setup does not apply, and those two routes do need catalog modes enabled for your organization.

Troubleshooting

• No StackJack sign-in ever appeared while creating the connector — the sign-in happens during creation, when ChatGPT reads the server's tool list, not after Create. If the dialog completed with no sign-in, that step did not run and the connector is permanently half-made: delete the StackJack app in ChatGPT and recreate it, completing the sign-in inside the dialog. Popup blockers are NOT the usual cause when the prompt never appears on any browser or machine.
• The Developer mode toggle is missing — you are on a Free account, on a mobile or desktop app (web only), on a Business workspace where you are not an admin/owner, or on an Enterprise/Edu workspace where an admin has not granted you Developer mode.
• The connector can't reach StackJack after creation — check that Authentication was set to OAuth, not "No authentication". Delete and recreate the app, completing the sign-in inside the dialog.
• Sign-in says no account was found — sign up in the portal first, or ask your team admin for an invite.
• Tools stopped working mid-conversation — an admin may have revoked your access or the connection; see Connection troubleshooting.

Establish the connection on the main endpoint (https://mcp.stackjack.io/mcp) FIRST — compact.stackjack.io is a catalog-tuning step for afterwards. Do not switch addresses while diagnosing a connection that has never worked.