I feel I’ve been left behind because all I use is Agents.md / Claude.md and Project.md. No skills, no tools. Everything I want my agent to do is specified in those two files. I also have a particular directory and file structure for things like scripts and sources which is indexed in the mds.
Fairly sure that your agent is using tools like “edit file” behind the scenes. The post is describing the fundamentals of how agent harnesses work, models don’t exactly have a way to edit files just sending an API request to and forth the provider in a chatbox.