That's about as helpful as ads we sometimes see for boots or tires, where they don't even tell you the size. At least he told you it's a 12 bore... which might mean nothing anyway. I have bought 12 gauge guns that turned out to be 16 gauge or 10 gauge. Sometimes wrong information can be a good thing.
At minimum, I think an ad for a shotgun should provide the make, model, gauge, barrel length, weight, chokes, LOP, overall condition, and price. And even with that bare minimum of information, a smart buyer will have lots of questions before dropping several grand on a gun.
Better yet would be a more complete description of condition, especially the barrels. I hate it when they say "some pitting", which could mean anything from very light and localized pitting to a veritable sewer pipe that may be beyond safe to even shoot. Bore and wall thickness dimensions are always nice to have, as are complete stock dimensions. But even many full time dealers don't do that. Being upfront about any issues such as dents, damage, repairs, or refinishing helps one to decide if the price is right. Then the return policy should be clearly stated. And of course, lots of good clear pictures, from buttplate to muzzles.