1. A method for operating an intelligent automated assistant, comprising: at an electronic device comprising a processor and memory storing instructions for execution by the processor: receiving a user request through a conversation interface of the intelligent automated assistant, the user request comprising at least a speech input received from a user; identifying one or more candidate domains relevant to the user request from a plurality of predefined domains, wherein each predefined domain presents a respective area of service offered by the intelligent automated assistant, and wherein the identifying is based on respective degrees of match between words derived from the user request and words representing vocabulary and entities associated with each predefined domain; and providing feedback to the user through the conversation interface of the intelligent automated assistant, wherein the feedback presents a paraphrase of the user request and elicits additional input from the user to specify one or more parameters associated with a particular candidate domain.