In this paper, we discuss a method and the associated tool support able to exploit Web services in model-based user interface development, starting with the results of a task analysis phase, and using the content of Web service annotations. The resulting environment is a powerful support for developing multi-device interactive applications based on Web Services, since it is able to generate usable service front ends specified in a variety of implementation languages. This is achieved through connecting preexisting Web services with the task model of the interactive application that has to be built. Then, the task model is used as a starting point for the generation of corresponding user es descriptions at different abstraction levels, through a number of transformations that aim to preserve the usability of the corresponding models or implementations. Keywords Model-based user interface design, Web services, Annotations, Task Models.