This project has been moved to: https://github.com/Plutonomicon/Shrinker This project contains tools for shrinking plutus scripts.
For plutus TX Shrinker is still somewhat expirementall. You can use either Shrink.PlutusTX.shrinkCompiled or Shrink.PlutusTXTH.shrinkCompiledTH. Shrink can be fairly slow on large scripts, hopefully this will improve with further development, but with plutustx there also seem to be laziness issues where shrink will run on the same script many times causing it to be much slower.
In most other cases Shrink.shrinkScript is the only function you need. If you want to exclude particular tactics perhaps because they are slow or have a bug you can use shrinkScriptSp (withoutTactics ["curry"]) scriptYouWantToShrink .
If you find a bug please report it on github or email me at brian@mlabs.city, a print of the uplc fed to shrink would be much appreciated. Feature requests and suggestions are also welcome.