The current API doc at https://github.com/openshift/os-client-tools/blob/master/express/doc/API states the following:

JSON String:
{
    ...
    'debug': 'true - An optional flag to get debug information returned'
    ...
}

There's a flag that would allow you to turn debug output on. This flag is a String whereas the Json standard clearly has a boolean value (which then would have boolean value that is NOT quoted).
The purpose of this issue is to track the progress on the server side.