All three players are currently on the 40-man roster, meaning the club will not need to make any corresponding roster moves. In addition, the Twins will add Class A Beloit manager Nelson Prada as an extra coach, and he'll wear uniform No. 65.
Benson, 23, hit .285/.389/.499 (batting average/on-base/slugging) with 28 doubles, four triples, 16 home runs, 14 stolen bases and 67 RBIs in 111 games with the Rock Cats this season.
Benson, drafted by the Twins in the second round of the 2006 First-Year Player Draft, was the club's Minor League Player of the Year in 2010, leading the organization with 27 home runs. Benson, ranked as the club's No. 5 prospect according to MLB.com, will wear uniform No. 63.
Parmelee, meanwhile, hit .287/.366/.435 with 29 doubles, five triples, 13 home runs and 83 RBIs in 142 games with the Rock Cats this year while seeing time at first base and right field.
The 23-year-old, who will wear No. 64, was selected by the Twins in the first round of the '06 Draft.
Tolbert, 29, was optioned to Rochester on Aug. 18 to make room for catcher Rene Rivera on the roster. Tolbert hit .202/.250/.271 with 11 RBIs and two stolen bases in 74 games with the Twins before being optioned.