I personally don’t deal well with evasive behavior, asking or being asked.
As for letting people know what you say yes to, all problems need the same evaluation therefore which leads to assumptions that you will say yes. Sometimes people don't ask and just assume. Another road to hell.
It's not evasive either. There's nothing to say that you're not going to sit there and work through it with them, engage with other people and come up with a solution based on pooled ideas.
Perhaps I should say I never say yes or no until the adequate amount of research has been done.
Consider your wife's coffee maker conversation practice for times where the stakes are much higher.
Problem: coffee machine not working.
Her representation of the problem: we need to buy a new coffee machine.
Really what’s going on: coffee machine needs cleaning properly but it doesn’t match the rest of the stuff in the kitchen now.
Edit: I'm sure this analogy probably works better for the folk downvoting when you look at it in terms of computation. Perhaps I should have write "the developer wants to rewrite this function as a microservice" whereas the real problem is "we need to fix this defect".
The real thing is the developer wants to write a new shiny microservice full of new bugs rather than actually fix the damn bugs. Same as my wife wants a new shiny coffee machine but doesn't want to clean the old one (which is a shitty job, which I did in the end anyway because I made the faulty decision of saying yes to myself too quickly. I also fixed the bug)
Yes, there's a bug in the production services, but maybe it's a nightmare to maintain and there are more and more bugs creeping in and a microservice might help make it more stable - and maybe the developers want more experience with new tech to grow professionally as well.
Probably after reading “No More Mr Nice Guy” everyone should read “How to Win Friends and Influence People”
I tend to respond with “let me sit down and think about this” then send them an email with their question and my answer. That gives both parties an opportunity to defend a position later or be honest about what the intent was as it’s amazing who emails get forwarded to when there’s a disagreement.