Yes, their is an inspection spot on the caliper, and you can actually see it from either side of the caliper, If they are very low, or the Rotor itself has grooves or lines drug into it, I would consider a front brake job immediately. possibly a rear as well.
It's really easy to pop the Caliper up, if I am not mistaken it is a Torx 45 bit, and you will be looking directly at sliding the caliper upwards to check the pads.
Inspect them for cracks or damaged edges, and replace immediately if you notice anything suspicious, it's cheap and quick to do and can save you money in the long run.
Don't forget if you dissassemble it is a good time to re-lube your slide pins with some silicone lubricant, and the surface of the brake caliper bracket that touches the pads with some silver anti-sieze.
It takes a decent mechanic around 10 minutes per side to do brakes, so about a 40-50 minute job if you do it at a decent pace, and an hour maybe if you are going to bleed the brake system as well, which is highly recommended.
Hope this helps bro, Good hunting.
1998 Mustang V6
CAI, Exhaust, Weight Reduction
16.5 1/4 Mile