That’s a tricky situation. It’s a pretty trad thing that games like Burning Wheel helped make explicit and untangle. I tend to play “you say you do it, you do it”. Although there probably is some wiggle room there. Like if a player says “how hard do I think it is to climb up that wall”, I’ll tell them a TN. Then they can say “no”.

That said – are you changing the TN on every roll of the encounter? I just set it once at the beginning, and then it’s up to the players when they want to tap out and stop pushing tolerance. That allows for gambling without hidden information.

I negotiate with the players on what the boons look like. Boon one: “I won’t kill you”, boon two: “You can sleep in the barn”, etc. Then we talk about those things. We also talk about what breaking tolerance looks like. Sometimes it’s pretty bad.