One of the most useful prompts I’ve picked up for Claude Code came from Simon Willison, who in turn got it from Jess Vincent. The idea: tell Claude Code to offload work it doesn’t need its full reasoning power for.
The original version is scoped to coding:
For all coding tasks use your judgement to decide an appropriate lower power model and run that in a subagent
I drop the “coding” part and just use:
For all tasks use your judgement to decide an appropriate lower power model and run that in a subagent
With that instruction in place, Claude Code will route the simple stuff — a file rename, a grep-and-report, a straightforward lookup — to a lighter model running as a subagent, and save your expensive Fable or Opus tokens for the tasks that actually need the reasoning.
It costs one line, and it works because the model is genuinely good at judging which tasks are trivial. You don’t have to specify which model or when — just tell it to use its judgement, and it will.