Increasing the length of a description field for an APIM operation causes a time out in the related MCP.

[amantaras]

When the  Open API description of an operation is larger than 1000 characters, the MCP creation fails, that's ok. But if you create the service with less than 1000 characters, the MCP is created, later, you can add more than 1000 characters and then the MCP times-out.