Frias (finger) was activated from the 7-day disabled list Wednesday.
Frias was place on the DL by Triple-A Columbus after sustaining a blister over the weekend, Tribe Insider reports.
Frias cleared through waivers and was outrighted to Triple-A Columbus on Sunday.
Frias was designated for assignment on Tuesday.
Frias could make the club as an eighth reliever if starter Carlos Carrasco opens the season on the disabled list, Ross D. Franklin of the Associated Press reports.
Frias is one of 20 pitcher in camp vying for the lone bullpen spot remaining on the team's 25-man roster, Paul Hoynes of Cleveland.com reports.
Frias was traded from the Dodgers to the Indians on Monday in exchange for cash.
Frias was designated for assignment by the Dodgers on Wednesday.
Frias was recalled from Triple-A Oklahoma City on Friday and placed on the 60-day DL.