A user specifies a natural language command to a device. Software on the device generates contextual metadata about the user interface of the device, such as data about all visible elements of the user interface, and sends the contextual metadata along with the natural language command to a natural language understanding engine. The natural language understanding engine parses the natural language query using a stored grammar (e.g., a grammar provided by a maker of the device) and as a result of the parsing identifies information about the command (e.g., the user interface elements referenced by the command) and provides that information to the device. The device uses that provided information to respond to the command.