[gwnn]

Suppose you bid 1NT forcing over 1M, intending to show a pushy 3 card limit raise.

Now LHO bids 2NT, RHO picks a minor (I guess the same can question could be about 1S-p-1NT-2S, p-3H, but let's stick to this one).

1M-p-1NT-2NT
p-3m-???

Suppose you judge that your hand has now got much worse than it was before this information. (lots of high cards/length in teh minors)

Can you pass 3m or do you need to complete your hand's description?

[whereagles]

You don't need to complete the description - judgement always comes before rules. You have to guess whether to bid or not.

It's because of sequences like this that I really prefer to bid limit raises in another manner, say, for instance 1M-3♣.

[helene_t]

This is awkward and one of the situations in which I would allow myself to fluke at the system. But I certainly wouldn't say that it is always mandatory to complete the hand description.

I suppose it would be right to double with
xxx
Kxxx
KJx
KJx
and pass with
xxx
KJxx
KJxx
QJ

[andy_h]

I don't think you need to complete the description. For example, if your hand has gotten worse in that it's super defensive in nature (lots of stuff in opponent's suit(s)) the last positive score could just be defending. Of course, it's pretty much up to judgement whether you think declaring or defending is better. In the example you provided where LHO has shown both minors, it'll be best to defend if you have stuff in the minors and only 3card support, as you'll know trumps are most likely going to break badly.
Partner could have doubled 2NT too.

[peachy]

Can pass, can double [cards & balanced], can bid 3M. Whatever looks right.

[Phil]

Of course you can pass. Not only have your minor holdings been devalued, you are also getting a nasty spade break with the stack on partner's left. TYO.