Glamorgan director of cricket Mark Wallace said: “Ray Toole is a player with a similar skillset to Mir, who has been playing in our second XI off the back of an excellent domestic season in New Zealand.
“To be able to call on him during this block as we try and manage workloads with six games in six weeks is going to be really beneficial for us.”
Glamorgan have so far used five overseas players in the 2026 season, with Hamza and Toole joining South Africa batter Colin Ingram in the squad.
Only two overseas players can feature in a Championship game.
New South Wales paceman Ryan Hadley was the overseas bowler for the first eight Championship games, but few Australians are allowed to play in the United Kingdom in August and September because of domestic commitments.
Afghanistan quick bowler Fazalhaq Farooqi, New Zealand all-rounder Jimmy Neesham and Australian seamer Nathan McAndrew were all used in the T20 Blast.
Toole, born in South Africa to British parents, has previous county experience with Essex and Durham, and has a career record of 150 first-class wickets in 48 games at an average of 27.
He took six wickets in the match for Glamorgan second XI against Worcestershire, gaining practice the week before his likely first-team debut.