A device, system and method controlling operation of a client device via an intermediation server are provided. The server maintains indications of predefined data descriptions, associated with respective provider systems, comprising a subset of given predefined data descriptions to be provided at a client device during implementation of a computing-process flow in conjunction with communicating with the respective provider systems. The server: provides, to the respective provider systems, a communication from the client device received in conjunction with implementing a given step of the computing-process flow; and receives, from a given provider system, a response to the communication. The server provides, to the client device: the response; and a predefined data description associated with the given provider system in the indications, the predefined data description provided at the client device in conjunction with the response causing the client device to implement the predefined data description, according to the computing-process flow.