Armagh started with intent in the sun at Clones and nearly had a score within the first two minutes as Caroline O’Hanlon’s flighted kick hit the base of the post.
McCoy then rifled home a goal for Armagh from a tight angle after being fed by O’Hanlon to open the scoring on five minutes.
Niamh Henderson added a point after a period of patient possession from the Orchard County before McCoy raced through and rattled home her and Armagh’s second goal on 13 minutes.
A free from Susie White on 18 minutes got Donegal on the board for the first time but Armagh went down the other end and pointed.
Eve Lavery and Grace Ferguson tagged on two more points as Armagh went in nine ahead at the break.
White got the first score of the second half from a free, but Lauren McConville replied at the other end.
McCoy then settled for a point after a slick move, when space looked to be opening up for another opportunity on goal.
Donegal registered their first point from play through Cait Gillespie and another through Katie Dowds as they continued to fight.
Armagh pulled away again with another clinical finish, as Coleman turned and fired low into the bottom corner for her side’s third goal.
Aoife McColgan opted to point from close range when she may have went for a goal, while Kelly Mallon and Lavery kept the scoreboard ticking over for Armagh at the other end.
Eve Gallagher scored two points in an impressive cameo off the bench as she traded scores with Meabh Lennon and Jodie McQuillan, with the holders easing to victory.
