Im not sure if this is a bug on the client library of it is a bug on anthropic, but I refactored my mcp... I have many versions of it: HTTP stateless, SSE... etc.
The thing is: It doesn't matter what the MCP does, if you have it registered, calls that takes longer than 2 minutes to the AI will always finish incomplete. If you remove the MCP, the task can take up to whatever (10 minutes)
So, it must have a bug somewhere when you add the MCP (im sure it is not timeout on my side). Or at least needs to be a clear documentation about this limitation