Hmm. I was going to say "assign it the value of true, and it returns true. Assign it the value of false, and it returns a contradiction", but on reflection that's not the case. If you assign it the value of false, then the claim becomes ¬(A is true), so it returns false.

So I was wrong - the proposition is a null proposition, it simply returns the truth value you assign to it. I don't know if ambiguous is the best way to describe it, but 'true' certainly isn't.

edit: perhaps cata's 'trivial' is a good word for it.