The Cursor'va which when translated meant "the eyes half-closed" was a group that served the System Lord Olokun and operated as an intelligence agents as well as a secret police on his behalf. They were masters of trickery and deception who spread misinformation by ensuring that false information reached the correct individuals. In this way, they ensured the spread of subterfuge against their Goa'uld master's enemies. They were entirely loyal to their master and primarily consisted of Jaffa though a small pool of candidates from other species were present in order to make use of their talents for specific missions.
Olokun had chosen a cadre of Jaffa for the task and placed them in a training program in order to heighten their awareness. This in turn allowed them to be placed amongst his worlds where they ferreted out spies and traitors amongst his domain. (RPG: "Living Gods: Stargate System Lords")