The use of middleware is one important approach to facilitating adaptation across wireless and mobile environments, where augmented service entities are composed and deployed to shield mobile clients from the effects of dynamic network characteristics. The MCL system provides a language-based approach to the building of mobile applications running in an adaptive middleware, MobiGATE. In particular, MCL is formalized by means of the design and development of a semantic model based on Z language, which can be used to analyze architectural descriptions and detect possible composition errors like feedback loops. To verify the semantic model and its ability to provide runtime checking of composition, we have developed and implemented a Java tool to demonstrate how Z semantic models are mapped into computational structures to provide on-the-fly verifications.