The Giants recalled McDonald from Triple-A Sacramento ahead of his start against the Padres on Monday.
McDonald served as the Giants' 27th man for Thursday's doubleheader against the Phillies, though he went unused out of the bullpen. Southpaw reliever Erik Miller (back) was placed on the 15-day IL in a corresponding move, so Monday's outing will likely be a spot start for McDonald. The 25-year-old right-hander has appeared in five games (four starts) in Triple-A and has a 5.40 ERA and 1.53 WHIP across 15 innings.