Cooper, 26, was the 17th pick in the 2008 draft out of the University of California-Berkeley. He batted .364 to win the Pacific Coast League batting title with Las Vegas in 2011 and was trying to claim the starting first-base job in Toronto last August when he suffered a career-threatening back injury against the Detroit Tigers.
Cooper got a new life in early April when Dr. Curtis Dickman, a Phoenix-based neurosurgeon, performed an innovative surgery to repair a herniated thoracic disc in his back. Cooper auditioned for multiple clubs in recent weeks before signing with Cleveland.
Cooper's deal includes an opt-out clause that allows him to sign with another club if he isn't added to Cleveland's big league roster in time to be eligible for the playoffs.