Hunter can earn an additional $1.4 million in performances as part of deal.
Hunter had surgery last July to repair the flexor tendon in his right arm after pitching in just five games. He had a 3.80 ERA in 64 innings in 2018 and has a 4.08 ERA and 21 saves in 12 seasons.
Righty reliever David Robertson was moved to the 60-day injury list to make room on the roster. He is recovering from Tommy John surgery on Aug. 15.