[jhumphries131]

A great question: We do plan to add content about the plugin protocol to this site. While documentation for plugins is light, it is easier to find and to get a working plugin than it is to find the information needed, for example, to write a tool that performs static analysis on a protobuf source files.

The biggest omission in the existing docs was the specification of the language.

Plugins generally require a library for a particular implementation language, so content we write would likely have to focus on a single language and library (at least to start). Whereas a spec is more broadly useful, regardless of what implementation language one is using with Protobuf.