The utilization of Web services is becoming a human labor consuming work as the rapid growth of Web. The semantic annotated service description can support more automatic ways on tasks such as service discovery, invocation and composition. But the adoption of existed Semantic Web Services solutions is hindering by their overly complexity and high expertise demand. In this paper we propose a highly lightweight and non-intrusive method to enrich the REST Web service resources with semantic annotations to support a more autonomous Web service utilization and generic client service interaction. It is achieved by turning the service description into a semantic resource graph represented in RDF, with the added tag based semantic annotation and a small vocabulary. The method is implemented with the popular OpenAPI service description format, and illustrated by a simple use case example.