Give them a blank page of paper and just tell them to "write."
This is something all DMs have to be aware of. You need to describe the environment in such a way that they can envision what is going on (I use minis and blocks made of clay for 3D effect to help with this). I do agree that knowing nothing about the environment, about the combat, about what obstacle they are facing would be annoying. The DM has to paint a picture, tell a story. The players then fill in the blanks and complete the story with how their hero would react.
I try not to set up situations where the players don't know what there options are. But in my example, they knew where the tower was. I was describing the dragon swooping in low and (not that I thought of it) they knew the top of the tower was above the dragon.
At that point my player asked to run up the tower (she has a lot of movement as a barbarian) at the end of turn 1, I had no clue what she was doing. The dragon ignored her and attacked her companions on the ground and on turn two she surprised me by jumping onto it's back.
She knew there was a dragon, and had a reasonable idea of it's tactics. She knew her character would rather go toe to toe with the dragon and decided it would be awesome if she could leap heroically on it's back. She didn't think in terms of the game mechanics, she thought "What would a half-orc barbarian do?" That's the whole point.
This was by no means a "blank page". If I ever have a character who doesn't know what to do (particularly new players) I will nudge them and give them hints and options. It doesn't take long before they start coming up with crazy awesome stuff on their own.
In previous editions (4E in particular, but 3.5 also had this somewhat) the rules for how you could interact were very detailed. In 4E, we had powers which most people I played with would print out and put in card sleeves. The game became a tactical war game. There's nothing wrong with that per se, but it wasn't what I play D&D for.
People stopped thinking "What would my raging half-orc barbarian do in this situation" they started thinking "what card can I play that would counter the card the opposition just played?"
I don't want to go there again.