Web services are software systems designed to support interoperable machine-to-machine interaction over a network. WSDL descriptions, often characterized as IDLs for Web services, are a key for Web service interoperability. Therefore, special care should be taken in designing WSDL descriptions. We present an approach that provides UML-based support to design and validate WSDL descriptions. To promote Web service interoperability, WS -I organization provides a Basic Profile that defines clarifications, refinements, interpretations and amplifications of Web service specifications, including WSDL. We propose UML-based profiles to define structural rules of WSDL documents as well as Basic Profile recommendations for WSDL descriptions. These profiles can be used to guide the user in designing correct and Basic Profile compliant WSDL descriptions and to check the validity of existing WSDL descriptions. We propose a method and tools for such validity checking, and demonstrate the applicability of the approach with a case study.