Donald turned in his best performance for Bath by kicking seven penalties from eight attempts but it was nip and tuck all the way through against fellow New Zealander Nick Evans, whose boot was also responsible for all his side's points.
Booth said: "The one thing about Stephen Donald is that he will never shy away from responsibility. He was very, very good tonight and showed his worth to the team. That has been very well received by fans and coaches and players alike.
"It was one of those really good team performances though. Everyone played their part. You want your big players, your senior players, your emerging players to put their hands up.
"It was a real team performance and a lot of people did that. They should be very proud of themselves. It was a massive performance on many levels."
Bath's never-say-die spirit was typified by former Scotland number eight Simon Taylor, who led a monumental effort in the loose to blunt Harlequins' dynamic attack, and Booth is looking for his side to emulate their performance at Leicester next week.
He added: "This is the rebirth of the new Bath, and what we are trying to get to.
"That should be the standard every week. Part of the evolution of this team is understanding that. We're down at Welford Road next week against Leicester, the side that everyone aspires to be. We are going to be tested even further.
"Everyone knows what a good side Leicester are - they're an outstanding side, well coached, well drilled. We are going to have to produce things like we did tonight to give ourselves the best opportunity."
Harlequins director of rugby Conor O'Shea took heart from his side's performance but believes errors at crucial points cost them dear.
"It's going to be a roller coaster of a season. We just have to stick to our guns the whole way through. The younger fellows who played tonight will have learned a lot," said O'Shea.
"The effort, the attitude of the boys was fantastic, right to the bitter end. But we have to look at ourselves. Every time we got field position and got points, we never dealt with the kick-off. And the number of penalties they got through our inaccuracy, clearing our lines, was just not good enough.
"But it's a 22-game battle. We got a point, should have been more, but all credit to them."
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