The main set of YaST Tools that help with developing modules. Examples: log viewer, generators, checkers.
Tools related to building an RPM package. They are needed only as a dependency for package building. They go into a separate RPM sub-package to reduce build-time dependencies. They are not expected to be directly used by developers.
Tools that help with mass changes to all YaST repositories living in the YaST organization. Examples: check out all modules, make a maintenance branch, or run a script for all of them.
Tools used to generate the YaST documentation. They are partly obsolete and are kept to be used as a base for a new documentation tool. They make sense only for a developer who is interested in generating new documentation.
Tools used to manipulate with YaST repositories at open build service. They make sense only for a developer with permissions to target repositories.