Do you have a producer or project manager, as well as the designer? I'd probably get cranky too, and go ask the producer whether we're prototyping / exploring, or working towards a known target / deadline
That kind of weak design is basically asking you to do the designing for them... which can be fine, if you know that's what you're supposed to be doing. I've worked on games where the programmers have knowingly been given only broad strokes and have been responsible for all the fine details, and in one case they developed new genre-defining gameplay systems. So it can be good to have the people with the power of implementation and iteration to have ownership over parts of the design... as long as they know they've got that responsibility. In other situation, the producer might be pissed that the programmers are faffing about in exploration/iteration mode, and the designer is wanking onto a page while a milestone deadline looms overhead...
No producer (yet, may hopefully change)
These ARE first pass, so it is, in a way prototyping. However, I would much rather be told what the first implementation should do.
For instance I Just asked the designer, "how should this be implemented the options are , A,B or C" to which the reply I got was "Yes, any of them". It seems the designer is afraid of commitment. Previously I have communicated verbally to him, which turned out to be a disaster.
I asked about X feature which I was to implement and he described the feature with some ambiguity. I thought fine, I can just do the obvious path. For example, I was to implement the character throwing a ball. It seems obvious to me, that when the ball is thrown, it is thrown with some force and is effected by gravity, has some sort of friction and restoration. After implementing it, I was told it was "just wrong" and that it would "obviously" travel in a straight line, not effected by gravity.
Yesterday I questioned him (again verbally) about something else, and resolved the ambiguities. But today he when questioned about something else he contradicted himself.
I am fine with things changing, but changing your idea of how something works day by day is frustrating. My idea how it should be is: Design it one way, play test, if it works great if not change it.
After the first instance of the ambiguities and my restricted freedoms (obviously the designer and I, don't share common ideas) I have stopped querying him face to face, instead I use the task manager comment system. So atleast I can refer to things he has said in the past on 'why I made it which ever way'
And before anyone asks we don't have a GDD *(or atleast one I can view)
and yes this is scrum, kinda, not really though :/