Aside from punishing fraud and enforcing contracts, the government can do nothing except slow the economy. Government interaction with the economy always involves picking artificial winners (those with campaign contributions) at the expense of everyone else (you and me). And that process never adds anything to the economy except friction.
Government interference in the economy also adds so many variables to economic performance that the future is too chaotic to predict. For instance, how do you account for a concept as squishy as "quantitative easing" in making predictions for inflation?