Keane is included in the Villa squad after signing on loan from Los Angeles Galaxy until the end of February.
Manager McLeish is refusing to reveal whether the Republic of Ireland international will start but has no doubt he will have a positive influence at Villa. He said: "In terms of the impact Robbie will have, he will have a great effect. His experience and knowledge in the dressing room should be worth its weight in gold."
He added: "In my playing career, bringing players into a club of that ilk was a case of not only looking for individuals to do well but looking for others to be inspired.
"Hopefully Robbie can push others to play their best football and I also think there's no bigger threat than someone coming in to take your place.
"I am sure the fans will enjoy seeing Robbie in a Villa jersey. We will just have to wait and see when that is. Robbie could make his debut but I am not going to reveal my starting line-up at the moment."
McLeish will hope Keane can help Villa put an end to a run of four successive home defeats if he is involved against the Toffees.
He said: "Desperate is a word I don't like to use but the home form certainly is something we want to put right.
"We have lost to three of the elite clubs and Swansea beat us after we got a great result at Chelsea which was a real kick in the backside. It's up to us. I do feel we have been punished for every little mistake at home. But the one thing we have to concentrate on is concentration.
"I feel sometimes we can have little lapses and two against Swansea cost us two goals. We have to concentrate from start to finish as we did against Stoke, Arsenal and Chelsea."