The Astros traded Cosgrove to the Nationals on Friday in exchange for cash, Brian McTaggart of MLB.com reports.
Cosgrove has spent the entire season with Houston's Triple-A affiliate, turning in a 4.30 ERA and 1.44 WHIP to go with a 29:21 K:BB through 29.1 innings. He didn't own a spot on the 40-man roster with the Astros, so he'll slot in as bullpen depth at Triple-A Rochester to begin his tenure with the Nats.