The file has hard limits, and a growing project hits all of them
.
Codex loads 32 KiB of instruction files and drops the rest, and the warning goes to a log file you never open.
The root file eats the budget first, so in a monorepo yours is the one cut.
Anthropic says target under 200 lines, because longer files reduce adherence.
Each rule you add weakens the ones already there.
The line about a service you rewrote in January still loads at full weight.
Nothing marks which rules still hold.
Do I delete my AGENTS.md?
No. Keep it for the things that are true for every task, like build and test commands.
The per-module detail that would bloat it goes to SenseLab.
What if an agent saves something wrong?
It gets saved. Report a couple of bad outcomes against it and its confidence falls to the bottom of the results.
Where two agents disagree, both versions are kept and the contradiction is flagged.
Do I have to change my prompts?
No.
Your MCP client picks up the instructions that tell an agent to check memory before it starts, and to report how the task ended.
