Well-intentioned describes a person, a plan, or an action where the aim was good — genuinely, kindly good — but the result was not. That gap is the whole point of the word. When an English speaker calls something well-intentioned, listen for the "but" that is almost always coming: "a well-intentioned policy that made housing more expensive", "my well-intentioned aunt, who told everyone about the divorce". It is a gentle word, because it gives the person credit for their heart while telling you their head or their timing failed them. It is not sarcasm and it is not an attack; it is what you say when you do not want to call someone stupid or selfish. Occasionally it is used purely positively — "well-intentioned people came from all over to help" — but even then the sentence usually admits somewhere that the help was clumsy. It is used both before a noun and after be. It is the sibling of well-meaning and, for a single act, well-meant; the three overlap so much that native speakers pick by rhythm rather than rule.