The new signing is set for his debut this afternoon, as Pools go to Fleetwood on the back of successive 3-0 defeats.
And, after Cooper admitted following last weekend's reverse that some of his younger players were in need of a lift after playing regular first-team football this season, the manager feels he has found his man.
"He can help the squad in general,'' he insisted.
"For James, Luke, Franksy, Nialle, even Monks, any player in a forward position, they should have respect for Marlon for the career he's had.
"What he has to show is that his career's not finished and that he's not just here to wind down.
"Marlon has to show he's here and raring to go.
"I know there were other opportunities out there for him and I'm delighted that he chose to come here and I know he'll be a positive role model for the younger players and have a positive impact on the pitch.''
Harewood left Bristol City earlier this month, following a change in manager when Steve Cotterill replaced Sean O'Driscoll.
He moved to Ashton Gate to pass on his experience to the younger players in the squad - in much the same way he will at Victoria Park.
"I believe we need a figurehead,'' admitted Cooper. "Marlon has come in with a completely clean outlook.
"He's enjoyed the atmosphere, he thinks we are a good club, he thinks we have a good bunch of young players and he's looking forward to being a part of that and having an impact.
"The important thing to me is not just what he can give us helping young strikers, it's what he can actually give us on the field.
"The first questions I asked him were 'are you still hungry?', 'do you still want to run?', 'do you still want to score goals?', 'do you still want to bully defenders?'
"As soon as he answered all those questions yes, for me it was a no-brainer.''
Cooper revealed that it didn't take long for Harewood to agree to move to Pools, where he could extend his playing career that has taken in 526 games, for nine different clubs, with 200 goals scored.
"I was keen to see if he was interested in coming here, contacted him and his agent, they quickly came up, took on board what we are trying to do and what I'd like him to do in his time here,'' he admitted.
"As soon as he left Hartlepool he phoned me and said he was in. So then it was a case of could we do it with the chairman and chief executive and here we are - done.''
And Cooper revealed the seeds of the move were sown at the City Ground, Nottingham in the late 1990s.
"During my career I tried to have an impact on players,'' he mused. "Post Stuart Pearce leaving Forest, I was captain so I always felt I had time for the younger players.
"I was only in my early 30s when I left and Marlon had just got into the squad.
"If people have the talent, whether you are 17 or 35 you have to bring them into the fold and let them play a part.
"You make the younger players feel they are part of what is going on.
"The one thing I've always done with younger players is help and encourage in terms of being a player myself and now as a coach and a manager.
"I took it all on board and me and Marlon had a very good relationship. I went back to Middlesbrough and his career went on to a different level.
"But the respect between us was still there and as soon as I told him what we are trying to do and develop here, he was in.''
While the last two established and experienced players to sign for Pools failed to make an impression, after both Steve Howard and Nobby Solano cut short their contracts, Cooper insisted Harewood is a different story.
"I don't see signing him as a risk,'' he said. "I think Hartlepool has had a hangover of things like that. No disrespect to anyone who has been here in the past, but he is a different kettle of fish - he is still fit, still strong and still hungry.
"The frustration at Bristol City is that he felt he was doing the job asked of him by Sean O'Driscoll as an older player, being a mentor to the younger players, but he still felt he was better than those younger players.
"Sean felt he had a role for him. My first question was 'are you still hungry?' - to score goals, to intimidate defenders, to still run and chase. The answer to them all was yes and I know he will be a positive asset in the dressing room and will help the young strikers and the squad in general.''