MCP Connector "Resource not found" - tools/call never reaches server

[jakelin]

Environment

• ChatGPT Apps SDK with MCP Server (TypeScript)
• @modelcontextprotocol/sdk with StreamableHTTPServerTransport
• Server exposed via ngrok

Issue

ChatGPT connects to MCP server during connector refresh, but tools/call requests never reach the server. Returns “Resource not found” and “Unknown Connector” errors.

What Works

• initialize - succeeds
• tools/list - returns tools correctly
• resources/read - widget loads correctly
• MCP Inspector - tools/call works
• Direct curl - tools/call works

What Fails

• ChatGPT UI - tools/call never reaches server
• Shows “Unknown Connector” and “No tool response”

Server Logs

Connector Refresh (works):

[MCP] method: initialize ✓
[MCP] method: tools/list ✓
[MCP] method: resources/read ✓

Tool Invocation (fails):

(No request received - tools/call never reaches server)

[riskbreaker]

This may be related to:

MCP Tool Invocation Issues with openai/fileParams

Issue 1: Tool invocation displayed but MCP Server receives no request Environment: MCP Server with openai/fileParams configured Tool requires user file access permission Expected Behavior: User triggers tool call Permission dialog appears (for file access) User approves MCP Server receives the request Widget loads after receiving response Actual Behavior: Frontend UI shows “tool is being called” status No permission dialog appears MCP Server receives no request Widget loads prematurely …

Connector operations intermittently become "Resource not found" after several successful calls

For the last ~5 days, connector calls have been failing intermittently. A given operation works correctly several times in a row. After some number of successful invocations, the next call suddenly fails with no response, on MCP server side I see no requests happening. Once this issue occurs, even previously working calls to the same operation start failing in the same way, until end of the agent operation. Interrogation of the agent reveals that is getting error in response of tool invocati…

I have the same issue, this happens sporadic, but it’s like 50/50 it will work inside ChatGPT or not.
Reported the bug already, but no response for about a month, since I got the problem the first time.
Usually to get it working again, I’m refreshing the connector and closing the webpage completely. Problem is worse on GPT-5.2 - it often just refuses to use MCP, like connector does not exist. With GPT-5 and GPT-5.1 tools are invoked, but no actual requests are sent to the MCP Server. At the time tool invocation not woring; triggered connector refresh operation (Init/New Session/List Tools/Read Resource) are sent to the server and processed correctly.
So MCP Connector init/auth always working, tool invocations are randomly failing.