The three fixes below came from one talk by Boris Cherny, who built Claude Code. None of them are settings. All three are about how you set the job up before the model ever runs.
1. Delete most of your instructions
He deleted roughly 80% of Claude Code's system prompt, and the tool got better. Long instruction files are usually a museum of old problems. Most lines were written to babysit a weaker model, and that model is gone.
What to do this week:
- Open your CLAUDE.md and read it as if you wrote it for a new hire who is already excellent.
- Delete every line that exists to stop a mistake you have not actually seen in the last month.
- Delete every line that explains something the model can read from the code itself.
- Keep only what is true, specific and impossible to infer: your stack, your conventions, your hard rules.
If a line would embarrass you to say out loud to a senior engineer, cut it
A good target is a single screen. If yours is longer, you are probably describing the model instead of your project.
2. Stop wording. Start experimenting
Rewriting a prompt over and over is guessing. The faster move is to treat it like an experiment: change one thing, run it, watch where it actually breaks.
The loop:
- Run the task and let it fail.
- Find the exact step it went wrong, not the general vibe that it was bad.
- Ask what the model was missing at that step: a file, a command, a way to check its own work.
- Give it that one thing. Run again.
Most failures are not phrasing problems. They are setup problems. The model could not see the file, could not run the tests, or had no way to tell whether it had finished. Fix the setup, not the wording.
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Get the full setup steps + the copy-paste setup prompt
The rest of this guide (2 more sections) opens right here. The setup prompt, one paste into Claude that sets it all up, comes by email only. Use your real address.
Unlocks: 3. Your tasks are far too small · The one page version
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