CLAUDE.md

CLAUDE.md works like an instruction manual that Claude Code reads before you put it to work. Think of it as the company rulebook a new hire finds on their desk on day one. Writing down "here's how we do things around here" means the employee follows that approach without having to ask every time.

This file exists because of mistakes AI coding tools often make: guessing instead of checking with the user, overcomplicating simple tasks, or touching parts of the code that weren't asked for. By placing a CLAUDE.md file in the project folder with principles like "don't guess, ask," "write only as much code as needed," and "only change what was requested," the tool refers back to these rules every time it starts a new conversation.

It can apply to a single project, or hold shared principles used across multiple projects. It's an easy way to get an entire team using the tool the same way.

Articles use phrasing like "the core guidelines are all captured in one CLAUDE.md file." A common misunderstanding is thinking this file contains actual code — in reality, it's a text document listing the rules and principles the AI tool should follow while working, not code itself.

Create a text file named CLAUDE.md at the top level of your project folder and write something like the following in it:

• If something is unclear, ask before proceeding instead of guessing
• Write only the minimum code needed to solve the problem
• Don't touch code unrelated to the request
• Before finishing, set your own success criteria and check against them

Then start working with Claude Code in the same folder and see whether the tool adjusts its answers and code based on what's written in this file.