McDonald (arm) was reinstated from High-A Eugene's 7-day injured list May 5 and made his season debut a day later, covering three innings and giving up one earned run on four hits and two walks while striking out three in a 4-2 win over Spokane.
McDonald spent the first month of the season on the shelf after he fell behind Eugene's other starting pitchers in his throwing program and required more time to build up at extended spring training. The Giants will likely be cognizant about managing the 22-year-old right-hander's innings this season, but he should be able to make one start or extended relief appearance per week now that he's back from the IL.