Imagine you are at an international policy conference. Someone says "Central Banks need to coordinate their monetary policies better". You nod your head wisely in agreement, along with everyone else. Because you know that what one central bank does affects not just its own economy but the economies of other central banks, so there are externalities, so they need to cooperate to escape a Prisoners' Dilemma equilibrium of Beggar Thy Neigbour policies. International policy coordination sounds really good, especially at an international policy conference.
Or maybe it's all BS.
I want to think about the alleged "Central Bank Coordination Problem" very abstractly. Is it a real problem? And if so, under what conditions? The important distinction is between monetary policy targets and monetary policy instruments.