Roberto Martínez has told Ross Barkley, the highly rated teenager, he will tolerate mistakes this season to enable "that little bit of magic" to develop in the Everton midfield. His promise comes amid efforts to sign Gareth Barry on loan from Manchester City.

Barry has been told he is surplus to requirements at City but has 12 months remaining on a lucrative contract. Everton are hoping for a compromise over the 32-year-old's wages with City and for the prospect of more regular first-team football in a World Cup year to entice the England international towards Goodison Park. The midfielder has several options, however.

Martínez is also looking to Barkley to improve Everton's midfield this season. The 19-year-old has carried high expectations at Goodison for several years but spent the past two seasons on the periphery of David Moyes's plans as the former Everton manager protected his recovery from a triple-leg fracture. Moyes withdrew the Liverpool-born midfielder to the reserve team two years ago after an error-strewn display at Blackburn, then loaned him to Sheffield Wednesday and Leeds United to gain competitive experience last term.

Barkley has featured prominently in pre-season under Martínez, however, and could start the new Everton manager's first game at Norwich City with Darron Gibson struggling with a knee injury. And Martínez believes he will reap the benefits of Barkley's rich potential by allowing the England Under-21 international to develop in Everton's first team.

The Everton manager said: "Football is a game of errors but what I look for from players is how you react to a mistake: does it stop you getting on the ball again? Do you come a bit more cagey? What I have seen from Ross is that it doesn't matter whether he makes a mistake, he is ready to get on the ball again. When a player does that, I have no problems whatsoever.

"Mistakes are going to happen and as a team you have to be prepared for that sometimes and get your team-mate out of jail. Ross has got such an incredible talent that we need to help him, so he knows how to control that. I have never seen Ross make a mistake and then be affected in the next action. You know that somewhere down the line he is going to get rid of those mistakes."

Barkley returned to the England Under-21s after a near two-year absence on Tuesday, appearing as a substitute and scoring in the 6-0 defeat of Scotland, but Martínez says there is no pressure on the academy graduate to make this his breakthrough season at Goodison.

"I wouldn't give him an ultimatum," added the manager. "I can only speak about what I have seen from a really impressive young man. He and John Stones have both been at a very good level this summer. John played against Juventus and was man of the match.

"Ross, in every game he has played, has shown that little bit of magic that not everyone has. I have been very impressed with both players. All I can say is that Ross and John are ready to give something to the first team. I would tell you otherwise if I didn't think they were. But I know they are ready."

Martínez spoke to Moyes about the challenges at Everton when he succeeded the Scot in June. "He was very, very helpful," said the Spaniard. "This is the third club I've managed here and, when you arrive at Everton, everything is in place. David Moyes did a magnificent job here." And he admits retaining the best of Moyes's Everton while developing a new style of play is the immediate aim for his first campaign as manager.

"Every time I've seen this group play we've had a real competitive edge and you don't want to lose that," he said. "August for us is not a time to set targets in terms of results or where we are going to finish. My objective is to bridge that gap between playing in a different way and how quickly we can win football matches with all these changes."