"Are you tired?"
Because you have not added the verb to be and it's unclear you you refer to: is it you, is it a third person? That's not what the original sentence reads.
In everyday speech only, with the right context you can omit the verb and get away with it, as in English: e.g. your partner comes home after work and lets out a big sigh and you reply 'Tired? / Κουρασμένος;' But otherwise, it just doesn't work and certainly not as a correct translation to the exercise. :)