The recon drone's only known function is reconnaissance, meaning they scan enemy territory for activity. They are unmanned, which means they either operate from a remote control, or are flown with a neural interface, similar to Aero-fighters.
A recon drone was searching through the wreckage of the Eurondan capital to see if there was any activity on the underground base. When it finished scanning, it flew back, only to be destroyed before arriving in its destination by Jack O'Neill in the unmanned squadron of Aero-fighters. (SG1: "The Other Side")