1. A computer implemented method for enabling an application for Conversational Understanding (CU) using assets in a CU service, comprising: receiving a selection of Application Programming Interfaces (APIs) that are associated with a domain to use in the application; automatically updating models for the CU service based on the selection of the APIs and the determined domain; receiving a Natural Language (“NL”) expression, wherein the NL expression may be used to interact with the application; rephrasing the NL expressions to generate at least one additional expression, wherein the at least one additional expression contains a different, way of expressing a meaning of the NL expression; and automatic updating the models for CU service based on the rephrased NL expressions; making the models available to the CU service.