Production debugging of APIs via Azure API Manager

The API manager tutorials show how debug the APIS using the TRACE button with predefined discrete variables, in isolation of other frontend elements ( EG an AJAX call from a HTML page). I'd like to get this level of debug information , but when the API is called from the original screen, so I can see how real data is posted to the API from the screen . The reason for this is because the inputs to the API are not discrete parameters, but rather a JSON string, which is parsed later in the API itself. How do I do that ?

Thanks in advance