Never do self-deprecating at an interview. Be realistic, sure, but if you mention something you're not good at, always follow up with a description of what you're doing to overcome those weaknesses. E.g. if you suck at presentations, say you're talking a course in public speaking, or that you always volunteer to make presentations anyway in order to get the practice.
If it were an interview, I would answer with whatever competencies the job required, but in slightly different words to the way it's written in the job description. So if the job requires attention to detail and doing regular tasks to a deadline, I'd describe myself as "meticulous, efficient and determined." Maybe "focused" or whatever. Personality traits that make you good at putting out accurate documents in a timely manner.
In short, if an interviewer asked me to describe myself in 3 words, I would absolutely not describe myself in 3 words.