Indeed, historically, central bankers have tended not to reveal such information, since they preferred discretionary policy over systematic policy. Of course, policymakers do not know with any degree of certainty how economic conditions will evolve. So they cannot and should not say with any certainty what policy will be in the future.
But policymakers can provide information about the factors that will influence their policy decisions. Some call this a policy rule. Milton Friedman advocated a rule in the form of a k-percent growth rate of the money supply. John Taylor devised a rule that depends on a measure of inflation relative to a target and some measure of resource utilization.