I just say something like "spawn an agent to review your plan" or something to that effect. "Red/green TDD" is apparently the nomenclature: https://simonwillison.net/guides/agentic-engineering-pattern...

I've also found it to be better to ask the LLM to come up with several ideas and then spawn additional agents to evaluate each approach individually.

I think the general problem is that context cuts both ways, and the LLM has no idea what is "important". It's easier to make sure your context doesn't contain pink elephants than it is to tell it to forget about the pink elephants.