Is "short paper" or "tool paper" valued less than full version paper?
I'm not sure that my area of CS is 100% comparable, since "tool paper" and "short paper" don't seem synonymous to me (I haven't seen any conference use "tool paper" as an official track name, but papers about tools feature regularly in the regular track).

But in my experience, yes, short paper is generally for lower-standard work, or more preliminary work. In fact, at all the conferences I have attended recently with regular and short paper tracks, the papers in the short paper track were mainly selected from the papers submitted to the regular track that didn't make the cut. Roughly speaking, first quartile gets to be full papers, second quartile short papers, the rest gets rejected. (Percentages vary with the quality of the conference, of course. Sometimes there's also a third tier of acceptance for posters.)