Maxwell, 29, is batting .241/.311/.387 with two homers in 40 games this season. For his career, he owns an OPS+ of 96 across parts of five major-league seasons.
Maxwell is capable of playing all three outfield positions. Potentially, the right-handed-hitting Maxwell could form a platoon with Jarrod Dyson in center for Kansas City, in addition to providing depth at the corners.
Per Bob Dutton, the Astros will receive minor-league right-hander Kyle Smith in return. Smith, age 20 and a fourth-round pick in 2011, has pitched to a 2.85 ERA, 1.18 WHIP and 3.31 K/BB ratio across parts of two minor-league seasons. Smith reached the High-A level this season and has 194 strikeouts in 176 2/3 career innings.