There are many, many people in this world who are not "normal." For example:

I ask: When will you come to my place tomorrow?
He says: Come tomorrow.
I ask: What time exactly will you come tomorrow?
He says: Hmm, in the afternoon tomorrow.
I ask: What time in the afternoon? I'll come pick you up.
He replies: Okay.
I say: Okay, damn~. I asked what time!

Basically, are you the same "communication species"? Biological evolution has led to asynchronous development. You: linear thinking, info-oriented, value time and schedules. He: vague expressions, low planning, emotion/currently oriented. These two types of people are neither better nor worse, but when placed on the same task, it’s a disaster. Some people: are not suitable for collaboration, not suitable for setting appointments, only suitable for "see you when it’s meant to be." It’s not that your communication skills are lacking; it’s that the other person is mismatched. Many people in this world are indeed not good at expressing themselves fully. But you have every right: not to guess along with them, not to cover for them, not to get drained because of their vagueness. You’re not busy; you’re clear, direct, and want to get things done.