Following the season-ending injury to Dan Butler in December, Posh were forced to use midfielder Harrison Burrows in defensive positions on the left-hand side in Championship matches. The youngster acquitted himself well, but McCann wants to use him in more advanced positions in League One next season.
Butler should be fit for the start of the season, but he can expect to be challenged for a starting place by Tomlinson. Tomlinson was signed from National League Eastleigh last summer, but the 21 year-old started just five games for Posh before joining League Two promotion-chasers Swindon Town on loan in January.
"Grant is happy with his options on the left of the defence,” Posh director of football Barry Fry said. “Dan Butler should be back and he believes Joe Tomlinson has the ability to play successfully in League One.
"We didn’t see a lot of him last season. The previous manager played him on the wing in the first game and then kept him back until a couple of games before Christmas.
"We let him go to Swindon and he went on to play very well for them. He was League Two player-of-the-month while he was there before he picked up an injury and came back.”
Tomlinson is a set-piece specialist, something Posh lacked last season.
McCann is after a right-sided defender to challenge Nathan Thompson for his spot in the starting line-up. A new centre-back could also be sought if teenage sensation Ronnie Edwards makes his expected big-money move away from London Road.