Agar, with his parents cheering from the stands, had barely made it back to the pavilion before the plaudits began pouring in.
Former England captain Vaughan got caught up in Agar's incredible batting performance.
"Never ever thought I would say I am disappointed an Aussie got out, but I really wanted Ashton Agar to get a 100 ... #Ashes," Vaughan tweeted.
Minutes later, veteran Indian commentator Harsha Bhogle, who regularly appears on international television and radio broadcasts, said he was moved by Agar's exploits.
"You think you have seen it all and then there comes a moment so fresh, so touching that you fall in love with cricket all over again," he tweeted.
Amazing debut
• Scored 98 from 101 balls on day two of the first test.
• 10th wicket partnership was a world record 163.
• Surpassed Tino Best (95 v England, 2012) for highest individual score by a No11.
• Surpassed Glenn McGrath (61 v New Zealand, 2004) for highest score by an Australian No11.
• Surpassed Australia's Warwick Armstrong (45* v England, 1902) for highest score and first 50 by a No11 on test debut.
• Surpassed previous highest 10th wicket partnership: 151, New Zealand's Brian Hastings and Richard Collinge v Pakistan at Eden Park in 1972-73.
• The first Ashes No11 in 117 years to topscore in an innings.
- AP