The three files: README, CLAUDE.md and PRD

⏱ 20 min6 steps

Every project I start begins with three files. They take about 20 minutes, and they save you from re-explaining yourself every time you open Claude.

You'll make them in your my-idea , so Claude can read what you found when you checked the idea. Claude interviews you, then writes them. If it rushes and writes all three at once, that's normal, and the fix is under that step.

folder A place on your computer that holds files and other folders, like a drawer in a filing cabinet. All words

Steps

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Go back to your idea folder in Claude Code
1. Open (Cmd+SpaceWindows key, type Terminal, press Enter).
2. Go to your my-idea folder with . Type this and press Enter:
  cd ~/Backyard/my-idea
  cd ~\Backyard\my-idea
3. Check the says my-idea.
4. Pick up where you left off. Type this and press Enter:
  claude -c
Terminal An app on your Mac where you type instructions instead of clicking on things. Claude Code works inside it. All wordscd The command that moves Terminal into a folder. Type cd, a space and the folder's name. It's short for change directory, an old word for folder. All wordsprompt line The line in Terminal that ends with a % sign. The word right before the % is the folder you're in. All words
You should see:
opens, with your idea check from last time above the line where you type.
Claude Code Claude, working inside Terminal. It can make files and run things on your Mac, with a safety checker watching what it does. All words
That's not what I see
It says "cd: no such file or directoryCannot find path … because it does not exist".
The my-idea folder isn't there. It comes from Check the idea first, so do that piece first, then come back.
It says "zsh: command not found: claudeThe term 'claude' is not recognized".
This Terminal window doesn't know about Claude Code. Close the window with Cmd+WCtrl+Shift+W, open a new one and try again. If it still says that, go back to Claude Code and .install Put a new program on your computer so you can use it. All wordssign in Tell Claude Code which Claude account is yours, so it knows you've paid for it. All words
Have Claude interview you and write the three files
This has Claude interview you, then write these three files:
- is the front door. What this is, who it's for and how to run it. It's for you in six months, and for anyone you hand the project to.
- is how Claude should work here: your rules, your voice, what not to touch. Claude Code reads it at the start of every in this folder, so you stop repeating yourself. Like the note you leave the babysitter: the more you say about the kids, the house and the rules, the better the night goes.
- is one page on the problem, who it's for, what "done" looks like and what's out of scope. It turns "check the idea first" into a page you can point Claude at.
1. Copy the prompt below.
```
I'm starting a new project and I want you to set it up with me before we build anything. Read idea-check.txt first if it's here. Then create three files in this folder. PRD.md: one page with these headings: The problem, Who it's for, How I know the problem is real, The smallest version, Done means, Not doing yet. Interview me to fill it in, one question at a time, and wait for my answer. Push back if an answer is vague. "Everyone" is not an audience and "it works" is not a finish line. When PRD.md is done, show it to me and ask what to change. CLAUDE.md: a note to you, for every session in this folder, with these headings: What this project is, About me, Always, Never, Style. Under Always, put: show me the plan before changing more than one file, and say plainly what you did not check. Under Never, put: never buy, subscribe or sign up for anything; never put passwords or card numbers in files; never delete files without asking. Ask me about anything you'd be guessing. README.md: what this project is and who it's for in one sentence, what it does, and how to run it. Leave anything we don't know yet as a short to-do. Don't write any code yet.
```
1. Paste it into Claude Code with Cmd+VCtrl+V and press Enter.
2. Answer each question in plain words and press Enter.
In Claude writes each without stopping to ask, so you'll read the PRD in the next step.
prompt What you type to Claude. A good one says what you want, how to work and what never to do. All wordsREADME.md The front door of a project. It says what the project is and how to run it, for you in six months and anyone you hand it to. All wordsCLAUDE.md A note to Claude about how to work in this project. Claude Code reads it at the start of every session in that folder. All wordssession One conversation with Claude Code, from when you start it until you leave. All wordsPRD.md One page on the problem, who it's for, and what "done" looks like. PRD stands for product requirements document. All wordsauto mode Claude works without asking, and a separate safety checker blocks anything risky. All wordsfile One document on your computer, like a letter or a photo. Files live inside folders. All words
You should see:
Claude asks you its first question about your project, and waits for your answer.
That's not what I see
Claude wrote all three files at once without asking me anything.
Type: Please slow down. Start over with PRD.md, and ask me one question at a time. It will.
I don't know the answer to one of its questions.
Say so, and ask what it would suggest. Or say: Put that under Not doing yet, I'll decide later. A PRD with an honest "I don't know" beats one with a guess in it.
Read PRD.md and fix what's wrong
This message asks Claude to show you the PRD it wrote.
1. Copy the message below, paste it into Claude Code and press Enter.
```
Show me everything in PRD.md.
```
1. Read every line.
2. If something isn't what you said, tell Claude what's true and ask it to fix it.
This page is the one you'll point back to when the project starts to wander.
You should see:
Your PRD in Terminal, under its six headings, from The problem down to Not doing yet.
That's not what I see
The PRD says things I never said.
Claude filled a gap with a guess. Tell it: The part about [this] isn't what I said. Here's what's true. Then add a line to CLAUDE.md: Never fill in my PRD with guesses. Ask me.
Start fresh and check Claude read your rules
This checks that a brand-new conversation picks up your rules from CLAUDE.md.
1. Leave Claude Code. Type this and press Enter:
  /exit
2. Start a brand-new conversation. Type this and press Enter, without -c:
  claude
3. Copy the question below, paste it into Claude Code and press Enter.
```
What is this project, and what are your rules for working in this folder?
```
That's the point of CLAUDE.md: a fresh start that already knows the project.
You should see:
Claude says what the project is and lists your rules from CLAUDE.md, without you explaining anything.
That's not what I see
Claude doesn't seem to know about the project.
Check you're in the right folder: type , then . Claude Code reads the CLAUDE.md in the folder you start it in, so start it in my-idea. If you're in the right place, type and check the file is called CLAUDE.md exactly, in capitals./exit Typed in Claude Code, it ends the conversation and takes you back to Terminal. All wordspwd The command that tells you which folder Terminal is in right now. It's short for print working directory. All wordsls The command that lists everything in the folder Terminal is in. All words
Add your first rule of your own
CLAUDE.md gets better every time something goes wrong. When Claude does something you didn't want, add one line so it doesn't happen again. You can ask Claude to do it with the message below.
1. Copy the message below and paste it into Claude Code.
```
Add one line to CLAUDE.md under Never, in my words:
```
1. Type a space, then your rule, like Never use long words.
2. Press Enter.
Two of the rules in my own CLAUDE.md files are already in yours: show me the plan before changing more than one file, and say plainly what you did not check.

When your project is ready for other people to use, Check it before you launch gives you another block for CLAUDE.md: check what a change affects, ask for evidence, and review the project before opening it to everyone. It includes the checklist and a you can keep in this folder.
command An instruction you type into Terminal. Your Mac does it when you press Enter. All words
You should see:
Claude adds your line under Never in CLAUDE.md and tells you it did.
That's not what I see
I can't think of a rule yet.
That's fine. Leave it. The first time Claude does something you didn't want, that's your rule.
Move your notebook into notes.md
Your notebook from Start here has your prompts, your and your decisions. Moving it into this folder lets Claude read it too, so you don't have to tell it again. This prompt has Claude make a file called notes.md from your notebook, in your words, and tells Claude to read it every session. If you don't keep a notebook, skip this step.
1. Copy the prompt below.
```
I keep a notebook about using Claude, and I want it in this project so you can read it too. Make a file called notes.md in this folder with these headings: Prompts that worked, My account, Decisions, Try next. Put what I paste below under the right headings, in my words. Don't change, shorten or tidy what I wrote. Leave out any password or card number if I pasted one by mistake, and tell me you did. Then add one line to CLAUDE.md under Always: read notes.md at the start of each session, and add a line under Decisions when we decide something. My notebook:
```
1. Paste it into Claude Code with Cmd+VCtrl+V. Don't press Enter yet.
2. Type a space.
3. Open your Claude notebook note. Select everything in it with Cmd+ACtrl+A and copy it with Cmd+CCtrl+C.
4. Click back in the Terminal window and paste it with Cmd+VCtrl+V.
5. Press Enter.
From now on, keep your notes in notes.md for this project. Your can stay for everything else.
account A sign-in with a company, like a domain, email or hosting. Whoever owns the account controls what's in it. All wordspinned note A note you've set to stay at the top of the list in Notes, so it's always the first one you see. All words
You should see:
Claude makes notes.md with your notebook under its four headings, adds one line under Always in CLAUDE.md, and tells you it did both. Your notebook shows as Pasted text and a number of lines. That's normal.
That's not what I see
My notebook is on paper.
Type the parts you still use after the prompt instead: the prompts that worked and your decisions matter most. It doesn't have to be all of it.
Claude changed my words.
Tell it: Put my notes back exactly as I wrote them. Then check notes.md again with: Show me everything in notes.md.
It sent before I finished pasting.
Paste the notebook in its own message, then press Enter.
I pressed Enter before I pasted my notebook.
Claude may ask you for the notebook. Paste it in its own message and press Enter.

Your challenge

For one week, every time Claude does something you didn't want, add one line to CLAUDE.md so it doesn't happen again. At the end of the week, count the lines.

Last checked 2026-10-17

Set up Claude Code › 2. Your project's files and rules