Systems, methods, and devices for two-way communication with a downhole tool string are provided. In one example, a method may include placing a downhole tool string into a pressure riser of a well while at least one component of the downhole tool string is not activated. Thereafter, a wireless control signal may be issued through the pressure riser to the downhole tool to cause the downhole tool string to activate the component. The wireless control signal may involve an acoustic signal, an optical signal, and/or an electromagnetic signal such as electrical dipole coupling or magnetic dipole coupling.