There are some attributes of processors that are useful to expose to users. Qualities like "contains sensitive property descriptor(s)", "has required property descriptor(s) with no default value", "uses Controller Service X", etc. can help users categorize these components.
Rather than require annotations (which requires a code change and release to update), Bryan Bende brought up querying these attributes at startup (NAR loading) and building simple lists/maps contained in memory.
Exposing these collections can help with searching/filtering processors in the Add Processor dialog, understanding immediate needs on template import / versioned flow snippet import, etc.