A method, apparatus and computer program product for creating and operating a conversational system are described. A user annotated Web API specification is received which includes a set of user annotations The user annotated Web API specification is analyzed to produce an action catalog. The action catalog includes a set of sentences, each sentence describing a respective Web API call. The user annotated Web API specification is also analyzed to produce a rule set, each rule in the rule set has a rule condition which corresponds to an input in the user annotated Web API specification. The action catalog and the rule set are provided to the conversational system. The conversational system uses a question answering (QA) system as a natural language understanding (NLU) component. When the conversational system receives a user input during a dialog between a user and the conversational system, the user input is interpreted by the question answering (QA) system to identify an action from an action catalog. The identified action is set as a goal for a goal-based reasoning engine. A response is issued to the user based on the identified action and results from the goal-based reasoning engine.