I don't understand what you mean, here. I'm not sure what you mean by 'true' or 'useful', I guess. I'm talking about true claims in this sense.

I mean what you mean by "true", or maybe something very similar.

By "useful" I mean "those claims that could help someone come to a decision about their actions"

Which one is that, and what does everybody already know it to mean?

It's what people say when they say "should" but don't precede it with "if". Some people on lesswrong think it means:

[you should do X] = [X maximizes this complicated function that can be computed from my brain state]

Some think it means:

[you should do X] = [X maximizes whatever complicated function is computed from my brain state]

and I think:

[you should do X] = [the statement that, if believed, would cause one to do X]