In some cases you will only need basic tools such as screwdriver, pliers, small adjustable wrench, and crescent wrench.
In other cases you will need more advanced tools such as an automotive-type tire iron to remove the torsion bar, electric drill with screw bits, adjustable wrench, breaker bar or pipe that fits over the square drive shaft on opener arms, longer screws for torsion spring replacement or some specialty tool engineered to fit a particular part of the opener.