Boris Cherny, the lead engineer on Claude Code at Anthropic, said something on stage at Y Combinator that cuts against almost every setup guide on the internet: delete your CLAUDE.md every six months and watch what the model does on its own.
He was specific about why. Almost every rule you saved was written for a model that needed the handholding. Opus 5 does not. Those instructions are not helping anymore. They are sitting in your context window, getting in the way, and you are the one still carrying them.
This is the list. Fourteen rows, one verdict each, and the reason behind it.
The keep or cut list
| IN YOUR CONFIG | VERDICT | WHY |
|---|---|---|
| CLAUDE.md, 200+ lines | CUT | Written for a weaker model. Delete it and start from zero. |
| Style rules the model already follows | CUT | Opus 5 defaults to clean, idiomatic code. You are restating it. |
| “Always explain your reasoning” | CUT | It already reasons. This only pads your output. |
| “Do not use emojis / em dashes” | CUT | One line of taste at most. Not a section. |
| Skills you installed and never used | CUT | Every one is context you pay for on every request. |
| MCP servers for tools you dropped | CUT | Dead connections still load their tool schemas. |
| Sub-agent definitions that duplicate | CUT | Two agents with the same job means neither is trusted. |
| Hooks that just print things | CUT | If nobody reads the output, it is not a hook. |
| How to run tests in THIS repo | KEEP | Not derivable from the code. This is real context. |
| Deploy and release steps | KEEP | Irreversible actions deserve written steps. |
| Non-obvious architecture decisions | KEEP | The why, not the what. Code shows the what. |
| Things the model got wrong twice | KEEP | Earned rules. Each one has a receipt. |
| Repo-specific naming or conventions | KEEP | House style it cannot infer from one file. |
| Credentials, paths, environment quirks | KEEP | Facts, not instructions. Cheap and load-bearing. |
Free, for your email
Get the full setup steps + the copy-paste setup prompt
The rest of this guide (4 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: How to Actually Do It · The six month reset, in five steps · What usually happens · The part nobody says out loud
50,000+ follow where these guides come from. No spam, reply “unsubscribe” any time.