The URL examples show that the GET response format is specified with a file extension like .json or .xml, but no extension is shown for the POST example and there's no explanation of the behavior of a successful POST response. I would suggest that the format for POST responses is specified the same way as GET responses so that an error message or a success message will be returned with the desired format.
Note that specifying this response format could be completely independent from the format of the actual payload sent in the POST request. That's not specified here anywhere either, but I'll note that as a separate issue.
The URL examples show that the GET response format is specified with a file extension like .json or .xml, but no extension is shown for the POST example and there's no explanation of the behavior of a successful POST response. I would suggest that the format for POST responses is specified the same way as GET responses so that an error message or a success message will be returned with the desired format.
Note that specifying this response format could be completely independent from the format of the actual payload sent in the POST request. That's not specified here anywhere either, but I'll note that as a separate issue.