A method of interfacing with applications, comprising: receiving, by a digital assistant component executed by one or more processors of a client computing device, a first input audio signal detected by a microphone of the client computing device; processing, by the digital assistant component using a natural language processing technique, the first input audio signal to identify an indication of an application; activating, by the digital assistant component responsive to the indication, the application for execution on the client computing device and cause the application to declare, to the digital assistant component via a protocol, a function the application is configured to perform; modifying, subsequent to activation of the application and based on the function declared by the application, by the digital assistant component, the natural language processing technique responsive to the function declared by the application, to increase a likelihood of detection of one or more parameters relative to the natural language processing technique not modified based on the function; receiving, by the digital assistant component, a second input audio signal detected by the microphone of the client computing device; processing, by the digital assistant component using the modified natural language processing technique, the second input audio signal to detect one or more parameters; determining, by the digital assistant component based on a comparison between the one or more parameters and the function declared by the application, that the one or more parameters are compatible for input into an input field of the application activated by the digital assistant on the client computing device; generating, by the digital assistant component responsive to the determination of compatibility and based on the one or more parameters, an action data structure for the application; and inputting, by the digital assistant component, the action data structure into the application via the protocol to cause the application to execute the action data structure and update a user interface element of the application. receiving, by a digital assistant component executed by one or more processors of a client computing device, a first input audio signal detected by a microphone of the client computing device; processing, by the digital assistant component using a natural language processing technique, the first input audio signal to identify an indication of an application; activating, by the digital assistant component responsive to the indication, the application for execution on the client computing device and cause the application to declare, to the digital assistant component via a protocol, a function the application is configured to perform; modifying, subsequent to activation of the application and based on the function declared by the application, by the digital assistant component, the natural language processing technique responsive to the function declared by the application, to increase a likelihood of detection of one or more parameters relative to the natural language processing technique not modified based on the function; receiving, by the digital assistant component, a second input audio signal detected by the microphone of the client computing device; processing, by the digital assistant component using the modified natural language processing technique, the second input audio signal to detect one or more parameters; determining, by the digital assistant component based on a comparison between the one or more parameters and the function declared by the application, that the one or more parameters are compatible for input into an input field of the application activated by the digital assistant on the client computing device; generating, by the digital assistant component responsive to the determination of compatibility and based on the one or more parameters, an action data structure for the application; and inputting, by the digital assistant component, the action data structure into the application via the protocol to cause the application to execute the action data structure and update a user interface element of the application.