I am trying to debug a TM integration with TMS, I was wondering if it is possible to get or intercept the XML contents that are transmitted from TM to TMS.
Enable verbose logging in the TM config file. Then check the log folder. Notice not every single call is included, but anything related to transferring content should be logged. Notice it overwrites the files, so if you send multiple items/jobs you will only have the files for the last item.
Alternatively disable HTTPS (might require reconfiguring TMS to allow HTTP only) and monitor the HTTP traffic.