An address under /.well-known that the portal does not serve, such as /.well-known/skills/index.json or /.well-known/openapi.json, answered the portal's start page with status 200, so a tool or an agent that looked for it could not tell that it does not exist.
This page needs JavaScript. The same content is available as Markdown: /changelog/2026-10-28-unknown-well-known-is-404.md. Every document for agents is listed in /llms.txt.