Capitalism is just economic freedom. It is where consumers, producers ,employers, employees all compete in an open marketplace. It is the absence of coercion, which can only be done by government because only government can use force. It's not a "tool," that doesn't make sense.
Very true.
Of course, government does have a role in capitalism. With no government, you have anarchy (in capitalism or any other system). You have the possibility that someone who accumulates enough money or goods or other resources, can start abusing those around him - kneecapping people who try to compete, stealing others' stuff, intimidating others etc. And govenment's proper role is to pursue, prosecute, and punish the ones who try that. Whether the abusers are citizens of your own country, or intruders (or attackers) from other countr(ies).
Government's role is NOT to set prices. Or wages. Or to take money from some people simply to give it to others. Or to decide what light bulbs we all should use, or what toilets, or what health care plans we should all sign up for.