Houston recalled outfielder L.J. Hoes, catcher Max Stassi (the club's 19th-ranked prospect) and infielder Jonathan Villar, and it selected right-handers Jorge De Leon and Nick Tropeano (No. 13 prospect) to the Major League roster, while lefty Darin Downs was activated from the 15-day disabled list.
To make room for De Leon and Tropeano on the 40-man roster, the Astros designated right-handers Paul Clemens and David Martinez for assignment.
Tuesday will be the first game for Lawless -- Bo Porter was dismissed from managerial duties on Monday -- and new bench coach Adam Everett. Houston's 40-man roster is full, and the Astros have 32 players on their active roster.
Joey Nowak is a reporter for MLB.com. Follow him on Twitter at @joeynowak. This story was not subject to the approval of Major League Baseball or its clubs.