I actually put a directive to always reply to me in French just to see if it was reading the rules. Spoiler: it was reading the rules and ignoring the ones that I cared about but it could tell me about it in French so.. victory?

I've only had good experience concluding any prompt with "and don't talk about it" but my colleague says it hampers the agent because talking to itself helps it think. That's not been my experience, and I vastly prefer it not spending tokens I give no shits about