[mschrage]

> In our timeline, maybe some file format could be standardized that describes the particular inputs and options a command takes, and e.g. shells would hook into it. Kind of like header files, but distributed either in a community repository or by each of the tools themselves.

This sort of sounds like what we're working on at Fig. We've defined a declarative standard for specifying the inputs to a CLI tool and have a community repo with all supported tools: https://github.com/withfig/autocomplete

Disclosure: I'm one of the founders