Does Your CLAUDE.md Keep Growing?

Every time Claude gets something wrong, it is tempting to add one more rule.

Do that for a few weeks and you have a very long file. Then your important rules get lost in it.

What is CLAUDE.md?

CLAUDE.md is the file Claude reads at the start of every conversation. Think of it as your standing instructions.

The guide to Claude Code from Anthropic, the company that makes Claude, says to keep it short, and gives you one test for every line:

"Keep it concise. For each line, ask: 'Would removing this cause Claude to make mistakes?' If not, cut it."

Their reason:

"Bloated CLAUDE.md files cause Claude to ignore your actual instructions!"

What should I do first?

Save a copy of your CLAUDE.md file. Keep it, so you can put a line back. Can't find the file? Ask Claude where it is.

Keep Claude's permission checks on. They are Claude's safety step before it changes or runs things. Don't switch them off to go faster.

Do not cut a line that protects something important, like a rule about not deleting or overwriting your files. If you're not sure, keep it.

How do I try it?

Ask Claude. Here is a prompt of mine you can copy:

"Read my CLAUDE.md. Do not change the file. List every line that no longer applies, and every line you would follow anyway without it. Explain each in a few words. I will decide what to cut."

You stay in charge of what gets removed.

Ask that question about each line on its list: would Claude make a mistake without this line? If not, it can go.

What stays in a training game?

Keep the rules that protect your content:

Rules about which answers are correct.

Rules about the approved wording learners must see.

Cut the notes that no longer apply, like a color you changed weeks ago or a bug you already fixed.

What's next?

Pick the one line you would cut first. Cut it from the real file. Work for a day. If something goes wrong, put the line back from your saved copy.

Sources

• Anthropic, "Best practices for Claude Code," section "Configure your environment," part "Write an effective CLAUDE.md": code.claude.com/docs/en/best-practices. Checked October 3, 2026.