A prompt generation engine operates to dynamically extend prompts of a multimodal application. The prompt generation engine receives a media file having a metadata container. The prompt generation engine operates on a multimodal device that supports a voice mode and a non-voice mode for interacting with the multimodal device. The prompt generation engine retrieves from the metadata container a speech prompt related to content stored in the media file for inclusion in the multimodal application. The prompt generation engine modifies the multimodal application to include the speech prompt.