Just this morning I have run across an even narrower case of how AGENTS.md (in this case with GPT-5.3 Codex) can be completely ignored even if filled with explicit instructions.

I have a line there that says Codex should never use Node APIs where Bun APIs exist for the same thing. Routinely, Claude Code and now Codex would ignore this.

I just replaced that rule with a TypeScript-compiler-powered AST based deterministic rule. Now the agent can attempt to commit code with banned Node API usage and the pre-commit script will fail, so it is forced to get it right.

I've found myself migrating more and more of my AGENTS.md instructions to compiler-based checks like these - where possible. I feel as though this shouldn't be needed if the models were good, but it seems to be and I guess the deterministic nature of these checks is better than relying on the LLM's questionable respect of the rules.

Not that much different from humans.

We have pre-commit hooks to prevent people doing the wrong thing. We have all sorts of guardrails to help people.

And the “modern” approach when someone does something wrong is not to blame the person, but to ask “how did the system allow this mistake? What guardrails are missing?”

I wonder if some of these could be embedded in the write tool calls?