[@spiral origin] 

I usually find that it depends heavily on the player. There are some that like having the most information possible and wanting to be "told" what it is that they should do in a scene. That's something more to discuss with the player though-what kind of style they like in a GM. I have one group of players that love the open-ended personal decisions that shapes the situation by what they do, but I also have one that'll sit and stare at me if I don't give a direction to go in.

Personally, I try to leave the player with a question they want/need to answer. It can be something simple as: where does this barred iron door lead and how do I open it? Or, I've learned there is a creature of this type in this area I need to be in, so how do I get past it? These are scenarios that are easily set up and designed without having too much or too little for the player to work with. They can play to their strengths to get through it-beating the door down rather than looking for the key or sneaking past the creature instead of running in to fight it. I think of it as a good open-ended scenario if there's more than one way to go about solving the problem. Each scene, or turn, still drives the overall story, but they got to choose how they wanted to solve it. 

The question can even go to the micro scale in combat: I know this wizard is going to cast this spell, what can I do to counter it or do I need to get out of the way? I find it an easy way to make sure that there is something for the players to think about before they make their next move.

In my opinion it only becomes railroading when you take away the players options. You tell them "You have to go this way if you want to advance the story" or "you can't go that way and do what you want to do." I'm not as familiar with text based GMing, but I know its very reactive when I'm running a game. Just kind of rolling with whatever they decide to do even if I hadn't thought it out is always a good fallback because it makes the player feel like they're driving the scenario. 

Sounds like you're already putting in a lot of thought for your players. Hope this helps make it a bit easier! Let me know if you have any other thoughts or questions