There's a 'should' either stated or implied.
Some confusion in that:
In economics “Normative Econ” often means axiom based approach. State “reasonable conditions on preferences and production functions” derive necessary implications. See… most of books like Mas Colell et al.
In common parlance, maybe in psych, I’ve hear “normative behaviour” used to mean something like “typical, normal, socially acceptable behaviour”
I don't think there's a perfect answer, but as a heuristic I defer to the logical positivists - if you can't even in principle find direct evidence for or against the statement by observing the physical world and you can't mathematically prove it, and on top of that it sounds like a statement about behaviour or action, then you're probably in normland.
'If you add 1 to 1 you should get 2' is not a statement people would necessarily consider normative.
Do "must" and "may" imply a should?