Leone allowed a hit and struck out two in a scoreless inning in Tuesday's 8-1 loss to the Angels.
Leone kept the blowout from getting worse in the ninth inning of the loss. The veteran right-hander last appeared in the majors with Cleveland, where he had an 8.38 ERA and 1.97 WHIP across 9.2 innings last season. He'll likely begin his San Francisco career in a low-leverage relief role.