In theory, an AI should be able to fetch the llms.txt for every library and have an actual authoritative source of documentation for the given library.
This doesn't work that great right now, because not everyone is on board, but if we had llms.txt actually embedded in software libraries...it could be a game changer.
I noticed Claude Code semi regularly will start parsing actual library code in node_modules when it gets stuck. It will start by inventing methods it thinks should exist, then the typescript check step fails, and it searches the web for docs, if that fails it will actually go into the type definition for the library in node_modules and start looking in there. If we had node_modules/<package_name>/llms.txt (or the equivalent for other package managers in other languages) as a standard it could be pretty powerful I think. It could also be handled at the registry level, but I kind of like the idea of it being shipped (and thus easily versioned) in the library itself.