The ability to provide appropriate and complete API descriptions to let users discover services that satisfy a set of requirements and compose them to fulfil more complex users’ needs is critical for the success of any modern ICT solution. Composition suffers from the lack of semantic matching between properties included in published API descriptions. The work presented in this paper addresses this issue by discussing the current formats and tools to build API descriptions, and presenting a method for extracting and associating semantic to properties. Such method relies on a revised version of Table Interpretation techniques to support semantic annotations of API properties. The objectives are to enrich the popular OpenAPI Specification format with semantic annotations, and add the functionality of semantic annotation and composition to the associated editor.