how is it different or better than maintaining an index page for your docs? Or a folder full of docs and giving Claude an instruction to `ls` the folder on startup?

Vercel think it isn’t:

https://vercel.com/blog/agents-md-outperforms-skills-in-our-...

It's hard to tell unless they give some hard data comparing the approaches systematically.. this feels like a grift or more charitably trying to build a presence/market around nothing. But who knows anymore, apparently saying "tell the agent to write it's own docs for reference and context continuity" is considered a revelation.