Hargam booked his ticket for Cheltenham with an effortless success in the John Smith's Scottish Triumph Hurdle Trial to give McCoy a quick double.
Settled behind the pace by the champion jockey, he travelled noticeably well throughout and jumped fluently on his third outing over timber.
Nicky Henderson sent him north on a search for better ground and he looked much happier than on his previous outing at Cheltenham, albeit not against the strongest opposition.
Donald McCain's Starchitect, who had chased home the winner's stablemate Peace And Co at Doncaster, gave vain chase but Hargam cruised six lengths clear to land the odds as the 4-11 favourite.
"AP (McCoy) thought it would be a good idea to come here to get him on some nice ground as he won despite of the soft ground last time," said Henderson.
"It's good prize money, the timing is good and we knew we'd get his ground.
"I was very pleased with that and AP was too. He jumped very well and travelled well and enjoyed it.
"I'll talk to JP but I imagine it's straight to the Triumph now, he doesn't need another run.
"Obviously we've got Peace And Co too and we're very lucky to have them both but there'll be more than just him to beat.
"I was really quite impressed to do, they weren't complete mugs he was beating."