Geospatial web service composition is a promising means for processing and analyzing geospatial data in distributed computing environments. However, convenient and effective approaches for assisting the invocation of geoprocessing workflows are still missing. Invocation errors frustrate users and eventually impact the popularity and application of geoprocessing workflows due to their complexity, inadequate description, constraints, and prompts for input/output parameters, workflow models, and their components. This article proposes an extension method for easy invocation of geoprocessing workflows to solve these problems. The proposed method facilitates the generation of Graphical User Interfaces (GUIs) and invocation messages, for human‐computer interaction and client‐workflow interaction respectively, by supplementing verification and constraints for workflow descriptions. Furthermore, by providing descriptive information, constraint mechanisms, and visualization functions, this approach enhances human‐computer interactivity during invocation. An exemplary user case demonstrates the feasibility of the method.