Your last comment, "it's a test" is in direct opposition to what the owner of a successful local recruitment firm advised. Her comments were that an interview is NOT a test; it's more like a first date.
"Do you like me? Do I like you?"

If a job applicant enters an interview with a genuine concern about how they can offer value to the interviewer, they can then have a meaningful conversation about value and the benefits that they offer. Far more important focus than wondering if my answers are too brief or too long.
1. What do you need?
2. Am I able to provide that?
3. Do I want to enter a long term relationship with you?