How to Install Claude Code & Second Brain OS on Windows

By Arbab | Published Oct 7, 2026 | 3:31 pm

You’ve got a Second Brain OS account. Now you and I are going to put it inside Claude Code on your Windows machine, so every agent, skill and tool you own is one slash command away.

 

Windows takes a couple more steps than a Mac. PowerShell needs admin rights, the install needs a PATH fix, and Git for Windows saves you trouble later. Each one is below, in order, exactly as you type it. Give it 20 minutes.

 

You’ll need:

Step 1: Open PowerShell as administrator

 

PowerShell is the Windows equivalent of the Mac terminal. Search for Windows PowerShell, right-click it and choose Run as administrator, then click Yes.

 

It opens in C:WindowsSystem32, the root of Windows. You don’t want Claude Code there. Move to your own user folder:

 

cd Users
cd <press Tab until your username appears>

 

Type cd with a space, press Tab until you see the user you log in with, then press Enter.

 

You’ll know this worked when the prompt reads C:Users<your-username>.

 

Step 2: Install Claude Code

 

Paste this and press Enter:

 

irm https://claude.ai/install.ps1 | iex

 

Give it a few seconds, up to a minute.

 

You’ll know this worked when PowerShell says Claude Code installed. It will also mention adding a folder to your PATH. That’s Step 3.

 

Step 3: Fix the PATH

 

The PATH is the list of folders Windows searches when you type a command. Until Claude Code’s folder is on it, typing claude throws an error. Paste this as is, it fills in your username for you:

 

[Environment]::SetEnvironmentVariable("Path", [Environment]::GetEnvironmentVariable("Path", "User") + ";$env:USERPROFILE.localbin", "User")

 

Now close PowerShell completely, reopen it as administrator, and cd back into your user folder as in Step 1.

 

Step 4: Run Claude Code and log in

 

Type:

 

claude

 

Choose Yes, trust this folder. If you aren’t logged in yet:

  1. Press Enter at the login screen and choose option 1 (Claude subscription).
  2. Your browser opens. Enter your email and click the sign-in link Anthropic emails you.
  3. Click Authorize.
  4. Back in PowerShell you’ll see Login successful. Press Enter.

You’ll know this worked when Claude Code’s prompt is waiting for you.

 

Step 5: Install Git for Windows

 

Recommended, not required. Claude Code is used to bash-style commands, and some later workflows won’t run in plain PowerShell.

  1. Download the latest version from git-scm.com/download/win.
  2. Run the setup and accept the defaults.
  3. Fully close PowerShell and reopen it.

Step 6: Connect Second Brain OS

  1. Go to secondbrainos.com/dashboard and open My Agents. It’s the same command Mac users copy.
  2. Copy the npx command. It carries your user ID and secret, so don’t share it.
  3. Open PowerShell as administrator, cd into your user folder (not System32), paste the command and press Enter.
  4. When it asks to install packages, type y and press Enter.

It looks like this, with your own values:

 

npx secondbrainos-mcp-server@latest <your-user-id> <your-secret>

 

Then close PowerShell once more.

 

Step 7: Check Second Brain OS is loaded

 

Open PowerShell, cd into your user folder, type claude, then:

 

/mcp

 

You should see secondbrainos connected. Select it and choose View tools to see what’s available. Then run:

 

/secondbrainos:start_secondbrainos

 

It’s free, and lists every agent and skill you own.

 

You’ll know this worked when your agents and skills appear. The list matches your purchases, so yours may differ from mine.

 

Step 8: Two settings that save you tokens

  1. Type /config.
  2. Set Thinking mode to false, so Claude Code doesn’t spend minutes thinking after every prompt.
  3. Go down to Model. Up and down arrows choose the model; left and right arrows change effort. Set it to low effort and confirm.
  4. Press Esc.

Then try it:

 

Create a system prompt for my AI receptionist

 

Claude Code picks the right Second Brain OS skill and asks you what it needs. It will ask permission for each action at first. That’s a good way to start; switch to auto mode with Shift + Tab once you trust it.

Troubleshooting

Problem Fix
claude is not recognised Rerun the Step 3 command, then fully close and reopen PowerShell.
Install fails with an access error PowerShell isn’t running as administrator. Reopen it with Run as administrator.
npx is not recognised Node.js is missing. Install it from nodejs.org, reopen PowerShell, rerun Step 6.
/mcp doesn’t list secondbrainos Close PowerShell and any Claude desktop app completely, reopen, run claude again.
Claude Code opened in System32 Type /exit, cd Users<your-username>, run claude again.
Fewer tools than expected Your tools match your purchases. Check My Agents in the dashboard.

What you’ve done

 

Claude Code runs on Windows with the right PATH, Git for Windows behind it, and Second Brain OS connected.

 

Your next action: open PowerShell, run claude, then /secondbrainos:start_secondbrainos, and pick one agent to try today.

 

On a Mac? The macOS version of this guide is shorter.

Ask me anything!

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