Open “System preference -> Security & Privacy -> Privacy -> Accessibility”
You can even run it while you're working, because you can set it not to wiggle your mouse unless your computer has been sitting idle for a while. Mouse Clicker just wiggles your mouse every once in a while, keeping your machine awake and happy. When you have some lengthy task for your computer to do, it's annoying to have to turn off your screensaver and turn off the sleep timer, only to have to turn it all back on again when you're done.
Mouse Clicker is most use to Auto click to keep your Mac awake.
