All three will be in camp with the Indians during Spring Training, which begins with pitchers and catchers reporting to Goodyear, Ariz., on Feb 18. Cleveland's position players are required to report on Feb. 22 with the first full-squad workout slated for Feb. 24.
The 37-year-old Hafner, who also took part in the organization's instructional league meetings this past fall, spent 10 of his 12 Major League seasons with Cleveland from 2003-12. He finished his career with the Indians with a .278/.382/.509 slash line to go along with 200 home runs, 558 walks and 688 RBIs in 1,078 games.
McDonald, 40, retired this offseason following a 16-year big league career that included parts of seven seasons with the Indians (1999-2004, '13). The former infielder turned in an 11.0 defensive WAR and posted a .972 fielding percentage (mostly as a shortstop) in 1,100 career games with eight teams. McDonald was selected by the Indians in the 12th round of the 1996 First-Year Player Draft.
The 47-year-old Nagy, who was in camp with the Indians as an instructor last spring, served as D-backs pitching coach from 2011-13 and had previous coaching stints in Cleveland's system. The former pitcher spent 13 of his 14 seasons in the Majors with the Indians, compiling a 129-103 record and 4.51 ERA in 313 games with the Tribe from 1990-2002.
Other special assistants to Cleveland's baseball operations department include Steve Lubratich, Dave Malpass, Don Poplin, Tim Belcher and Edwin Rodriguez.
Jordan Bastian is a reporter for MLB.com. Read his blog, Major League Bastian, and follow him on Twitter @MLBastian. This story was not subject to the approval of Major League Baseball or its clubs.