You don't have to reexplain the business context. Save it to the mdc file if it's important. The added benefit is that the next real person looking at the code can also use that to learn - it's actually cool for having good up to date documentation is now an asset.
Do you find your agent actually respecting the mdc file? I don’t.
There should be no difference between the mdc and the text in the prompt. Try something drastic like "All of responses should be in Chinese". If it doesn't happen, they're not included correctly. Otherwise, yeah, they work modulo the usual issues of prompt adherence.
I think this is how certain LLMs end up with 14k worth of system prompts
This is the piece that confuses me about the comparison to a junior or an intern. Humans learn about the business, the code, the history of the system. And then they get better. Of course there’s a world where agents can do that, and some of the readme/doc solutions do that but the limitations are still massive and so much time is spent reexplaining the business context.