In some application domains as composite software, ranging from search engines, to more general applications, like cooperative and distributed applications or e-business and e-commerce applications, more and more rely on capability description. In this paper we try to highlight some concepts concerning capability description and discovery, and we discuss the relationship between capabilities. Specifically, we choose a capability description language, as and extension of ALN Description Logics languages. The mediation services are expected to play an important role in helping automated processes to access heterogeneous information. They are not Yes/No answers from the mediator, when no single object meets the search criteria, they may be cooperative answers to make a composite answer.