Is A Promise Of Nothing Ever Good Enough?

Is a promise of nothing, a promise of something?
Let’s define a promise. Let’s say a promise is a concept predicated on a statement, deed or behavior not ever to be broken. So a promise of nothing or of ‘no something’ is a promise void of direction, focus or goal. Let’s say an agreement is a legal term for a promise. Is what we exchange in commitment vows a promissory note of something and, what is that something that we are promising?
Pre-nuptials spell out something related to tangible goods, but what are we spelling out with our promises?
What is the something never to be broken? Is a promise of nothing or something ever good enough when not spelled out?