Thompson was recalled from Triple-A Memphis on Saturday.
Thompson hasn't pitched in the majors in over a month but will provide an extra arm in the bullpen after Genesis Cabrera was sent down Saturday. Thompson posted a 2.45 ERA and 0.95 WHIP in 22 innings over 12 appearances (one start) with the Cardinals earlier in the year and should serve mainly as a middle reliever now that he's back in the big leagues.