Current developments in the field of Computer Aided Control Engineering (CACE) have a visible impact on the design methodologies and the structure of the software tools supporting them. In this paper we try to define requirements on design methodologies used in CACE enhancing efficient flow of information between the tools supporting the following phases of the design process. The major conclusions of the paper are related to identification of the factors affecting the software tool integration in a way needed to facilitate design "interphase" communication. These are: standard application interfaces, dynamic data exchange mechanisms, code generation techniques and general software architecture requirements.