Systems and processes for operating an intelligent automated assistant are provided. For example, an intelligent automated assistant obtains a static vocabulary entry for an application and registers the static vocabulary entry to a knowledge base. While the application is running, the intelligent automated assistant receives a request from the application to register a dynamic vocabulary entry, and also registers the dynamic vocabulary entry. Upon receiving a user input, the intelligent automated assistant determines whether a matching vocabulary entry for the application has been registered and causes the application to perform a task based on the matching vocabulary entry.