McCaughan's contract was selected by the Mariners on Wednesday, Ryan Divish of The Seattle Times reports.
McCaughan made 10 starts at Triple-A Tacoma to begin the year, and he posted a 3.97 ERA and 46:13 K:BB in 59 innings during that time. The Mariners haven't yet announced what the right-hander's role in the majors will be, but he could be a candidate to join the rotation since several of the team's starters are dealing with injuries. Outfielder Dillon Thomas was sent down in a corresponding move.