Free markets do not claim that. Those against free markets try to twist free market to claim them. Free markets to claim that boom and bust cycles are smaller, that monopolies are harder to maintain. Monetary policy is by definition not part of a free market (though many people try things that look like monetary policy if they have power the market isn't free). External costs/tragedy of the commons is something free market doesn't do well, which is why free market advocates have complex ideas that boil down to internalizing those costs.