OpenAI App Submission – Tool scan failed: Internal service error

[isaac-b]

We’re in the process of submitting our MCP to the app directory, and get the error “Tool scan failed: Internal service error”.

Troubleshooting:

1. The OAuth flow successfully ran.
2. Using ngrok we confirmed our service was called & returned a valid 200 response for the tool/list.
3. Our full MCP is ~54k tokens, resulting in the 500 error.
4. We truncated the tool/list, and found that the tool scan worked when the MCP definition was below ~32k tokens. This worked with any arrangement of tools; the max-size seemed to be the only limitation.

I’ve submitted a support request to support with specific identifiers. Given the response status is 500, is this a bug?

[isaac-b]

[O-mkar]

Did anyone find any solution to this issue?

[isaac-b]

No solution has been found, still causing a 500 error.

The error has been:
• Attempted by multiple users
• Attempted in fully verified org
• Attempted on multiple MCP servers
• Attempted in different orgs

All of the above trigger the 500 error when the MCP size is larger than an unclear limit. Extensive triage reports have been sent to support.

[jhariani]

We are having the same issue. Does anyone have a work around?

[isaac-b]

No solution has been found yet!

[bil]

Hi, any updates on a potential fix?

[isaac-b]

After ~2 months, OpenAI got back to me. They said they have no plans to change this limit; we ended up completely re-working our MCP to fit under the token limit. Support said:

• Each individual tool definition must be under 5,000 tokens. This includes the tool name, description, and input schema.
• All tools combined (including name, description, and input schema) must be less than 16000 tokens.