ChatGPT can talk to any remote MCP server through Developer Mode, and it accepts Streamable HTTP, which is what this endpoint speaks. There is one real catch and it is worth knowing before you start: ChatGPT's custom connector takes a URL and supports OAuth or no authentication — it gives you nowhere to type an Authorization header. TopClozer anticipates exactly this and accepts the key as a URL parameter instead, which is why the connector works at all. It is also why this page spends more time on key hygiene than the others do.
Authentication in one line
What ChatGPT gets
4 LinkedIn tools plus the workspace ones. All read-only — ChatGPT can research LinkedIn; it cannot contact anybody through it.
Setup
Check your plan
Developer Mode is available on Plus, Pro, Team, Enterprise and Edu. Free ChatGPT cannot add custom connectors at all, and no configuration changes that.
Turn on Developer Mode
Settings → Apps → Advanced settings → Developer mode. ChatGPT warns you that custom connectors run third-party code on your behalf. That warning is accurate and applies to us too.
Generate a key you can revoke
Developer → Create a key (MCP), and mint a separate one for ChatGPT rather than reusing the key in your editor. The reason is the next step.
Add the connector
Paste the URL below, with your key in the query string. Then treat that URL as the secret it is — see the warning under the config.
The config
Lives in ChatGPT → Settings → Apps → Advanced settings → Developer mode. Swap the key and you are done.
https://topclozer.com/api/mcp?key=tcz_live_YOUR_KEYTreat that URL as a password
Verify it works
Ask ChatGPT: “which TopClozer tools do you have?” — 12 should come back. To check the endpoint independently of the client, an unauthenticated GET returns the server name, version and tool list:
curl -s https://topclozer.com/api/mcpIf the tool list is empty but the connection succeeded, the problem is the key rather than the URL: the MCP handshake is answered before authentication, on purpose, so a client can complete initialize and then surface a clean 401 on the first real call instead of failing with an opaque connection error.
ChatGPT gotchas
Specific to this client. None of these are guesses — each one has cost somebody an evening.
- A key in a URL is a key in a log
- Query strings end up in browser history, in proxy logs and in screenshots. This form exists because ChatGPT gives no alternative, not because it is good practice. Mint a connector-specific key so you can revoke it alone, and revoke it the moment it appears anywhere it should not.
- Free ChatGPT cannot do this
- Custom connectors are gated behind Developer Mode, which is a paid feature. There is no workaround at the server end.
- OpenAI does not vet custom connectors
- ChatGPT says so when you enable Developer Mode: a custom MCP server is a third-party service under its own terms. That is a reasonable thing to be careful about, and reading what a server exposes before connecting it is the correct instinct — ours is listed in full on the tool reference.
What it will not do
- Send anything. No invite, message, reply, follow or like. Every tool reads except pause_campaign, and outbound stays behind human approval in the product.
- Work without a connected account. The LinkedIn tools run through a sender account in your workspace. Without one they return a readable error saying so — accounts for agents covers how teams get one.
- Run unlimited. 30 LinkedIn calls per 5 minutes per workspace. An agent retrying in a loop is the request pattern that gets accounts restricted.
FAQ
Why can I not use a bearer token like everywhere else?
Because ChatGPT's connector dialog has no field for one. It supports OAuth or no authentication, and this server authenticates with a workspace API key, so the key travels in the URL instead. The endpoint checks the Authorization header first and falls back to ?key= precisely for clients like this.
Is the ?key= form less secure?
The credential is identical; its exposure is different. A header is not written to browser history or proxy logs and a query string sometimes is. Use a separate key for this connector, and revoking it in Settings takes effect on the next call.
Will ChatGPT be able to message people on LinkedIn?
No. Every tool is read-only except pause_campaign. It can research; it cannot contact anyone.
Other clients: Cursor · VS Code · Claude · the tool reference