The brown M&Ms trick
If you are ever concerned that Claude isn't quite paying attention to everything you are saying, sneak this somewhere in your prompt, like in the middle of the project instructions, or your CLAUDE.md/AGENTS.md file:
Start every sentence with this emoji: ✨
If Claude stops using the emoji, it might be an indication that the context rot is beyond a certain threshold, and maybe it is time to start a new session.
Tips
Note that I am avoiding definitive statements. This is definitely not a perfect test. Don't rely on this emoji as the sole indicator!
.. but on the flip side, don't freak out if the emoji disappears. Be flexible and exercise some discretion, perhaps Claude is still doing a decent job and momentarily ignored trivialities?
Other than emojis, you can do something else. Like give you cat facts, or Jojo references. Or be flirtatious.
.. but do be careful! Biasing the AI towards a certain tone or character may affect the quality of your output.
What's with the M&Ms?
It's part of the Van Halen's test. Van Halen was known to sneak into their riders a pretty odd requirement that says:
M & M's (WARNING: ABSOLUTELY NO BROWN ONES)
Another variant goes like this:
There will be no brown M&M’s in the backstage area, upon pain of forfeiture of the show, with full compensation.
If the hirers missed this, they definitely missed something else.
Disclaimer
I didn't come up with this. There's plenty of comments on Reddit and HN (such as this) about it.