"He's a Premier League striker, he went to Villa for £4m-£5m. He's got all the abilities to have a big impact."
Harewood, who is on loan at Molineux from Aston Villa until the end of the season, has not played much football over the past two seasons but McCarthy believes this hasn't affected his fitness levels.
"At 29 he's at a good age. He wants to get back playing football which he hasn't been able to do because the team (Villa) have been winning, but he's as fit as a flea.
"Like everyone else who goes out on loan he's hungry to play."