Ping brings up a good point, you need everything spelled out in detail on the bid, and on the contract when it gets to be that time. This means all equipment with make and model, not just 2HP Pentair pump, instead Pentair Intelliflow model VSR 011018 variable speed pump or whatever model you get. The same goes for everything else, filter, plaster finish, name and style of type of stone, etc.
Here is a paraphrasing of a real world example of problems that can come up, I don't recall the outcome of this first example, but a few months ago we had there was a member with a new pool build in Texas, they had opted for travertine decking around the pool (travertine is much cooler than concrete on bare feet), for some reason the sub contractor that was installing the travertine installed what is normally more expensive polished travertine instead of the rougher brushed finish travertine the pool owner had expected and discussed with the pool builder, as a result the surface was extremely slippery when wet, unfortunately the contract simply read X sq feet of travertine decking, and did not specify finish, which potentially shifted any liability away from the pool builder, and perhaps shifting the cost to tear out and redo to the pool owner.
In the past we have also seen many problems come up with gunite pools not being built to their specified depth, usually due to excess gunite being used in a pool that was dug to the specified depth making the pool shallower than desired. Therefore it is important to specify exact, minimum or a an accepted range of dimensions including depth, and if that depth is to the edge or the water line along with remedy requirement if not built to contract. In the past we have seen examples of this where a pool was specified with a 3.5 ft minimum depth to water line and built with 3 ft depth, then the pool builder was only willing to give something like a 10% discount on the pool cost due to variance, which may seem fine to the pool builder but not to the pool owner who had 36 inch long arms and wanted to swim laps without scraping his knuckles.