Claude Code · built-in command

Your CLAUDE.md is holding Opus 5.5 back: clean it with one command

Most CLAUDE.md files are full of rules written for older Claude models. Opus 5.5 follows instructions more literally, so leftovers like "always double-check your work" make it slower and pricier. Claude Code's built-in /claude-api skill has a prompt-audit that finds them and proposes fixes as a diff.

Came from the Reel? You commented AUDIT. Here is everything, with one-tap copy.

Before you start: You need Claude Code v2.1.221 or later. /claude-api is a bundled skill, so there's nothing to install. Update first with: claude update

Setup

Update Claude Code
claude update
Open your project and run the audit
/claude-api prompt-audit
Read the proposed diff, keep what makes sense, then accept
Apply? y / n

All 2, step by step

The habits it hunts

The audit flags instructions written for older models in your CLAUDE.md, skills, prompts and tool descriptions. On my own 4 skills it found 16. These came up most.

ALL-CAPS commands with no reason ("NEVER", "YOU MUST"). Opus 5.5 takes them literally and over-applies them. Keep the rule, drop the shouting, add the why.
Rules that contradict each other ("max 59 seconds" in one place, "the user's length wins" in another). The model has to guess which one you meant.
Output-length clamps ("nothing longer", "1-2 lines only") that cut the useful part of the answer.
Double-check rituals and step-by-step scripts for things the model no longer needs walking through.

Tip: Nothing changes until you approve the diff.

Official docs →

No Claude Code? Do it by hand

Paste your CLAUDE.md or system prompt into any Claude chat with this prompt.

Paste the prompt and your file.
Apply the cuts you agree with.
Run a normal task and compare the result.

Prompt

Audit this prompt for Opus 5.5. Flag instructions written for older models: ALL-CAPS commands with no reason, rules that contradict each other, output-length clamps, double-check rituals, and step-by-step scripts for simple tasks. Show the fixes as a diff and explain each cut in one line. Don't change anything that's a real project fact. [paste your CLAUDE.md]

Tip: Keep facts (paths, commands, conventions). Cut habits.

Tip: Anthropic reported that on a customer-support assistant, cleaning prompts this way cut costs about 9% and raised accuracy about 2 points on the same model.