Last I checked Alloy was another wonderful specification language with bad or non-existent tooling.
I love the Alloy Analyzer. It's simple to use, you can visualize instances, it can point to UNSAT cores in the Code.
(I wish it had a easy-to-use command-line or API so it would be easier to build a Web-based version of it.)
(Some of these might just be problems on Windows)