A publicly reachable HTTPS MCP endpoint, which is what heymcp share gives
you
OpenAI’s documentation lists Developer mode as a Pro/Plus/Business/Enterprise/
Education feature. We found it present and usable on a Free account in
August 2026, so check your own settings before assuming you need to upgrade.
ChatGPT calls these Plugins now, not Connectors. The old Connectors URL
redirects there.
2
Click Developer mode
It’s the last row on the Plugins panel, and it jumps you to the Developer
mode section of Security and login.
3
Toggle it on
It carries an ELEVATED RISK badge, because it lets you add servers
OpenAI hasn’t reviewed. That’s exactly what a HeyMCP tunnel is.
Settings → Plugins → Developer mode
There’s a second toggle here, Enforce CSP in developer mode. Leave it as you
find it; it governs network access for dev-mode apps and is unrelated to
reaching your tunnel.
Plugins in the left sidebar, then the + button to the right of the
search box.
3
Fill in the New Plugin dialog
Field
What to put
Icon
Optional. PNG, 256×256 or larger, max 10 KB
Name
Anything — My local MCP
Description
Optional, but worth a line
Connection
Leave on Server URL
URL
https://amber-jetty.t.heymcp.dev/mcp
Authentication
No Auth, unless you shared with --bearer
Then tick I understand and want to continue. The Create button stays
disabled until you do.
The New Plugin dialog, filled in for a HeyMCP tunnel with No Auth
4
Create
ChatGPT connects and discovers your tools.
The Tunnel toggle next to Server URL is ChatGPT’s own built-in way of
reaching a server on your machine. You don’t need it with a HeyMCP URL — and
choosing Server URL is what gets you the timeline, the handshake report and the
stable address across restarts.
Watch the inspector as you click Create — INIT, NOTIF and LIST rows
fingerprinted as ChatGPT should appear straight away.
ChatGPT supports three modes for a custom connector:The Authentication dropdown offers three options:
Option
Works with HeyMCP
No Auth
Yes. This is the normal choice.
OAuth
Only if your own server implements it. HeyMCP is not an authorization server; it forwards /.well-known/* so your server’s OAuth metadata is discoverable through the tunnel.
Mixed
OAuth for tool calls, no auth for initialize and tools/list. Same caveat as OAuth — your server provides it.
If you shared with --bearer, OAuth and Mixed are
the only options that carry a credential, and neither sends a static token. In
practice, share without --bearer for ChatGPT unless your own server
implements OAuth.
Pick the right mode when you create the connector. Choosing the wrong one is
the most common cause of ChatGPT prompting for authentication over and over
after setup.
Same as Claude.ai: descriptions up to about 1024 characters, names up to 64.
Anything longer is truncated or dropped — the handshake report flags it first.
Developer mode isn’t on. Settings → Plugins → Developer mode. It is
web-only, so this won’t work from the mobile app.
It keeps asking for authentication
The plugin’s auth mode doesn’t match your tunnel. If you shared without
--bearer, Authentication must be No Auth. Picking the wrong mode is
the most common cause of repeated auth prompts after setup.
The Create button is greyed out
Tick I understand and want to continue in the risk box. Create stays
disabled until you do.
An error toast, and nothing in the inspector
ChatGPT never reached the edge. Check the URL and confirm heymcp share is
still running.
Connected, but tools are never used
Check the handshake report for missing or
over-long descriptions.
Custom connectors are not reviewed by OpenAI. That warning is aimed at
connectors from third parties — but it’s worth remembering that a HeyMCP tunnel
URL is reachable by anyone who has it. See
What is exposed.
⌘I
Assistant
Responses are generated using AI and may contain mistakes.
