APIM MCP Client Timeout when API returns code

[ch-rob]

Reproduced by brucemoe@microsoft.com. Also working with anishta@microsoft.com and vitaliik@microsoft.com.

I've reproduced the issue on Bruce's Canary instance: /subscriptions/34b0ca36-cb2f-44d5-824b-1a5c51a6ec79/resourceGroups/bmoetest/providers/Microsoft.ApiManagement/service/mcp-test-canary-skuv2-710

Using APIM's MCP wrapper around a Python ACA API. The end API is a simple Python Lorium Ipson API hosted in ACA to return sample code files if given the following size parameter:

• Size = 11: Return sample code that will cause the issue
• Size = 12: Return sample code that will cause the issue
• Size = 13: Return sample code that will not cause the issue
• All other sizes returns that number of Lorium Ipson paragraphs

All calls succeed when tested via the APIM test pane, but the first two return "MCP error -32001: Request time out" when called through the MCP Inspector tool or other MCP clients.

Tested with MCP Inspector v0.15.0 (and others), Github Copilot in vscode 1.103.2.