Tirade - Presidential Powers

Once again we have the usual fight on our hands about whether a President can go to war on his say so alone.  I can remember the same argument when Reagan went into Grenada; Bush 41 went into Iraq the first time; Clinton went into Bosnia and Oh the squealing about Bush 43 going into Iraq again.  Even if he had over 30 countries, the backing of the UN and a vote in favor by Congress.  But can we please settle the issue.  Under what circumstances can a President go to war - or sort of war or bomb or whatever aggressive behavior?  Surely it's not beyond the pointy heads in Washington to get a formula that we can all understand and then we'll all - including future Presidents - know the limits and boundaries.  Come on People!