Well you don't mention which model, but in general the stabilizer link attaches to the front control arm at one end, and to the sway bar at the other end. I think that for all 1999 models it's a rod with a ball joint at either end and its purpose is to distribute some of the cornering force that causes body roll (sway) from the outside wheel to the inside wheel in a corner, improving stability by keeping the car level. Typical failure is the ball joints wear out, and you'll hear small clunks from the front end when one wheel hits a small bump, or during cornering transitions. And yes if it's loose, and a lot of them are wearing out now, it needs to be replaced for safety inspections in most states/provinces. It's considered part of the suspension thus it must be secure & have no excess play.
-Chris