"I'm happy to walk away from the game," McGrath told a Kensington Oval news conference ahead of Saturday's World Cup final against Sri Lanka.
"I feel it's in a good state, there are a lot of good young fast bowlers coming through in Australia and I'm happy with what I've achieved and what the team has achieved as well.
"Stuart Clark, Mitchell Johnson, Shaun Tait, Brett Lee and Nathan Bracken, there's so many guys coming through. The fast bowling cupboard is very full and the selectors have got plenty of options."
McGrath, 37, has enjoyed an illustrious career since making his international debut 14 years ago.
He is the most successful pace bowler in Test cricket history - only spinners Shane Warne and Muttiah Muralitharan are ahead of him - with 563 wickets and in all international cricket he has taken 943 wickets.
This World Cup has seen him become the tournament's most successful bowler of all-time.
Ahead of Saturday's final, he had 70 wickets in tournament history; the 25 in the 2007 edition was already a record for a single event.
But the New South Wales seamer, whose English-born wife Jane has suffered several bouts of cancer, was in no doubt about the timing of his decision to bow out.
"I'm looking forward to retirement. But I still love playing. This tour, I've probably felt more relaxed than I ever have. I've enjoyed it and maybe that's the reason why I've played well. The team playing well also helps.
"When I get back home, the first thing is to spend some time with the family and get away from cricket."
McGrath's Test career ended at his home Sydney Cricket Ground in January.
Along with fellow retirees, Warne and batsman Justin Langer, he had helped Australia wrap up a 5-0 Ashes series thrashing of England.
But he said the lure of a World Cup had kept him going.
"I probably would have finished my career before this if it hadn't been a World Cup," said McGrath who was appearing in his fourth straight final on Saturday.
He played in Australia's defeat to Sri Lanka in 1996, followed by trophy-winning triumphs in 1999 and 2003.
"I've got a lot of memories of Barbados as well. This is where I took my first five-for (five wickets in an innings) in international cricket.
"To me a perfect way to finish would be with another five-for, a win, walk off and happy days."
McGrath, who grew up on his family's farm in rural New South Wales before moving to Sydney, said there was no secret to his remorseless accuracy.
"The less complicated you make things, the less things can go wrong. If you can bowl 99 balls out of 100, hitting the deck and the top of off-stump, you'll take wickets.
"When I've given that advice, I'm sure people have walked away disappointed. But it's worked well for me over the last 12 or 14 years."
And Sri Lanka captain Mahela Jayawardene vouched for its effectiveness.
"It's always a challenge facing him because he's always asking questions, not just me, probably any other batsman in the world would say this," said Jayawardene.
Asked about the batsmen he most admired, McGrath singled out Brian Lara, the former West Indies captain who also retired at the World Cup, and India's Sachin Tendulkar.
"The two standouts are Brian and Sachin. I feel Brian was probably in front of Sachin when they were both at their peak."
As for fast bowlers, McGrath nominated West Indies' Curtly Ambrose and Pakistan left-arm great Wasim Akram.
"They were two guys I really looked up to. Ambrose, the way he hit the deck when he really wanted to crank it up and Akram, what he could do with the ball both new and old and the way he just powered through the crease, both those guys were amazing bowlers."
However, Australia captain Ricky Ponting said McGrath's class was undeniable as well.
"There's no doubt we are going to miss him. He's one of the all-time greats and what he's been able to do for Australian cricket over such a long period of time is unbelievable. I don't mind saying I shed a tear at the SCG after he'd played his last Test."
And with the final also marking John Buchanan's last match as Australia coach before his retirement, Ponting added: "There are lots of good memories.
"Hopefully, there's another great memory we can take from this game and give both Glenn and John the appropriate send-off."