It's a philosophy that embraces fatalism and keep you on the path of finding your nature and then keeping on that path, just being yourself, without regards for external influences.
The notion of duty is however very strong in stoicism: social duty is part of your nature. You have to accept your obligations and perform them the best you can, without search for external rewards.
All in all, stoicism is a search for personal tranquillity, inner peace. It's not even a philosophy of efficiency, at least I've never seen it described as such.
Stoicism doesn't rely on "tools" either. You can be a milkman and still adopt stoicism as your personal philosophy of life.
Duty is a very big part of stoicism: it acknowledges that we live in a social world and that our nature, our role, requires that we perform our duties to the best of our abilities. This is the only way to achieve some sort of peace, by removing the fact that you need something eternal to yourself to find satisfaction about what you do.
So, you can be a janitor, collect rubbish, be a developer, a manager, an office worker, a CEO, it doesn't matter. You'll only achieve peace if you find your own way to derive satisfaction in whatever fortune you find yourself in at a given instant. In short: accept what fate threw at you, don't sweat what you can't control, and learn to make the best of it.
I'd say it's a perfect philosophy for today.