The Rangers designated Richards for assignment Wednesday.
Richards earned the save against the Athletics on Wednesday, retiring the only batter he faced on one pitch.
Richards (0-1) took the loss Friday as the Rangers fell to Atlanta 6-3, giving up two runs on two hits and a walk in an inning of work.
Richards will serve as the opener ahead of primary pitcher Spencer Howard during Friday's game against Atlanta, Levi Weaver of The Athletic reports.
Richards struck out one in two scoreless innings, allowing two hits and a walk in a 2-0 loss Sunday in Oakland. He did not factor into the decision.
Richards allowed two runs on two hits and two walks over one inning in Thursday's 10-5 win over the Angels.
Richards (finger) was reinstated from the 10-day injured list Thursday.
Richards (finger) is scheduled to begin a minor-league rehab assignment with Triple-A Round Rock on Tuesday.
Richards will begin the season on the injured list due to a blister, Evan Grant of The Dallas Morning News reports.
Richards agreed to a contract with the Rangers on Thursday, Evan Grant of The Dallas Morning News reports.