Carroll has rejoined Newcastle on an initial 12-month contract, eight-and-a-half years after leaving St James' Park, following his release from West Ham in the summer.
Bruce said: "Well it was just a conversation with Andy, he was desperate, a bit like me I suppose, to come back. And of course, the big question mark of everybody is can we get him back quickly and can he stay fit?
"If he stays fit, then a fit Andy Carroll is as good as you are going to get. We'll do our utmost.
"He is determined to come and be successful again here, it's his hometown club. It was a no-brainer really, one of them ones where you're delighted to do it."
The 30-year-old, who has had long spells on the sideline with injury, has picked up nine England caps and returns a more experienced player.
Bruce added: "He's not young Andy Carroll anymore, he's at that veteran stage, but make no mistake when the club sold him for record fee he was the best pound-for-pound centre-forward there was around in the country.
"Unfortunately in the last couple of years, in particular, he has picked up a nasty ankle injury, so he can do a lot off the pitch in the dressing room and that's why we really bought him as well to give us that hand in the dressing room."