Sarries were under the cosh late on at Vicarage Road as Gloucester were awarded three successive penalties but elected to scrum in a bid to force a try.
McCall reserved special praise for late replacement Nick Auterac, who only celebrated his 20th birthday last month but played a key role in the scrum in Sarries' late rearguard action.
"The team showed a lot of character today," said McCall, whose side are up to second in the table.
"We brought on Nick, who hasn't much Premiership experience, for a couple of scrums on our line - so maybe it wasn't the kindest thing I've ever done to him.
"But that last scrum was amazing. He's a really talented kid who's come through our academy. We're well blessed with looseheads and Nick is going to be the future."
McCall warned that, with the Heineken Cup starting next weekend, there will be no rest for England stars Chris Ashton, Owen Farrell, Brad Barritt and Alex Goode after the Twickenham triumph over New Zealand.
"We've got Munster back-to-back so everyone will be in next week," said McCall, who rested South Africa hooker Schalk Brits and Scotland captain Kelly Brown after their international exertions.
He added: "We take a long-term view on all these internationals but the England players will be involved in the Munster games.They will be rested after those games because it's important we look after them."
Fly-half Charlie Hodgson kicked 23 points for Saracens on his return to the side after four weeks out with a fractured cheekbone, while Richard Wigglesworth went over for the hosts' sole try in the second half.
Gloucester, who had two players sin-binned, replied with tries from prop Dan Murphy and flanker Akapusi Qera, with Billy Twelvetrees kicking their other 13 points.
And Gloucester's director of rugby Nigel Davies felt his side were unfortunate to emerge on the wrong end of a tight contest.
He said: "It could have gone either way at the end. There were a couple of big calls that the referee had to make. Sometimes you get them, sometimes you don't.
"You wonder when the first two scrums (at the end of the match) weren't sufficient to merit a penalty try. On another occasion they would have been, I'm sure.
"On the third one, to be fair, they got the hit and it made it easy for the ref."
Davies added: "I was pleased with the way my team stuck to their task. We ended up outscoring Saracens two tries to one which is no mean feat here.
"This team are working for each other, which is really important. There were areas of our game I wasn't particularly pleased with but we know we're a work in progress."
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