A computer-implemented method for interpreting user input to perform a task on a computing device having at least one processor, comprising: at a processor, detecting whether a hands-free mode or a hands-on mode is active; at an output device, prompting a user for input; at an input device, receiving user input; at the processor, interpreting the received user input to derive a representation of user intent, characterized in that the interpreting comprises: interpreting the user input as text; generating a set of possible candidate interpretations of the text; parsing the candidate interpretations of the text and generating a set of possible semantic interpretations from the candidate interpretations; processing the set of possible semantic interpretations to obtain task steps; determining the representation of user intent from the set of semantic interpretations based on the obtained task steps; at the processor, identifying at least one task and at least one parameter for the task, based at least in part on the derived representation of user intent; at the processor, executing the at least one task using the at least one parameter, to derive a result; at the processor, in accordance with the derived result and responsive to detection that the device is in a hands-free mode, generating a dialog response based on the derived result in a speech-based output mode comprising paraphrasing at least a portion of the user input in spoken form including generating speech using a plurality of voices to differentiate paraphrased user input from other spoken output; and at the output device, outputting the generated speech; wherein, responsive to detection that the device is in a hands-free mode, at least one of the steps of prompting the user for input, receiving user input, interpreting the received user input, identifying the at least one task and at least one parameter for the task, and generating the dialog response is performed in a manner consistent with limitations associated with the hands-free mode as compared to the hands-on mode. at a processor, detecting whether a hands-free mode or a hands-on mode is active; at an output device, prompting a user for input; at an input device, receiving user input; at the processor, interpreting the received user input to derive a representation of user intent, characterized in that the interpreting comprises: interpreting the user input as text; generating a set of possible candidate interpretations of the text; parsing the candidate interpretations of the text and generating a set of possible semantic interpretations from the candidate interpretations; processing the set of possible semantic interpretations to obtain task steps; determining the representation of user intent from the set of semantic interpretations based on the obtained task steps; interpreting the user input as text; generating a set of possible candidate interpretations of the text; parsing the candidate interpretations of the text and generating a set of possible semantic interpretations from the candidate interpretations; processing the set of possible semantic interpretations to obtain task steps; determining the representation of user intent from the set of semantic interpretations based on the obtained task steps; at the processor, identifying at least one task and at least one parameter for the task, based at least in part on the derived representation of user intent; at the processor, executing the at least one task using the at least one parameter, to derive a result; at the processor, in accordance with the derived result and responsive to detection that the device is in a hands-free mode, generating a dialog response based on the derived result in a speech-based output mode comprising paraphrasing at least a portion of the user input in spoken form including generating speech using a plurality of voices to differentiate paraphrased user input from other spoken output; and at the output device, outputting the generated speech; wherein, responsive to detection that the device is in a hands-free mode, at least one of the steps of prompting the user for input, receiving user input, interpreting the received user input, identifying the at least one task and at least one parameter for the task, and generating the dialog response is performed in a manner consistent with limitations associated with the hands-free mode as compared to the hands-on mode.