The Giants recalled Koss from Triple-A Sacramento on Wednesday.
With Matt Chapman (abdomen) being placed on the injured list, Koss is back with the big-league club for the first time since May 15. Koss made the Opening Day roster for San Francisco but batted just .071/.133/.143 in 15 plate appearances before being demoted. The 28-year-old played in just three games for Sacramento before suffering a fractured wrist. After completing a rehab assignment, Koss has been cleared to return to action and will start Wednesday at shortstop while batting ninth versus the Diamondbacks.