Install an MCP Server in Claude Desktop on Windows: Full Guide

Windows adds a couple of wrinkles that the Mac guide skips over — Notepad's save-as-type trap, the double-backslash JSON requirement, and npx sometimes hiding from Claude Desktop even when it works fine in your terminal. Here's how to navigate all of it.

What You'll Need

• Claude Desktop — from claude.ai/download
• Node.js — LTS version from nodejs.org. The installer handles everything including npx.
• A text editor — Notepad works, VS Code is much better

Step 1: Find the Config File

Windows stores the Claude Desktop config here:

%APPDATA%\Claude\claude_desktop_config.json

Open it fast: press Windows + R, type %APPDATA%\Claude, press Enter. Explorer opens right in the Claude config folder.

Or use Claude Desktop's shortcut: hamburger menu → Settings → Developer → Edit Config.

Step 2: Open the Config File

Right-click claude_desktop_config.json → Open With → Notepad or VS Code.

File doesn't exist?

1. Open Notepad
2. Type {}
3. File → Save As → navigate to %APPDATA%\Claude\
4. Change "Save as type" to All Files (*.*)
5. Save as claude_desktop_config.json

Step 3: Add Your Skill

{
  "mcpServers": {
    "memory": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-memory"]
    }
  }
}

The backslash problem

If you ever need a local file path in your config, Windows backslashes must be doubled in JSON. C:\Users\Me\tool becomes C:\\Users\\Me\\tool. For skills installed via npx, you don't need any paths — just the package name.

npx not in PATH?

Run this in Command Prompt:

where npx.cmd
# C:\Program Files\nodejs\npx.cmd  ← use this full path

{
  "mcpServers": {
    "memory": {
      "command": "C:\\Program Files\\nodejs\\npx.cmd",
      "args": ["-y", "@modelcontextprotocol/server-memory"]
    }
  }
}

Step 4: Save and Restart

1. Save — Ctrl + S
2. Fully quit Claude Desktop — right-click tray icon → Quit, or use Task Manager to end the process
3. Reopen from Start Menu or taskbar

Windows vs Mac: Key Differences

Troubleshooting

"npx is not recognized"

Node.js isn't in your PATH. Either reinstall Node.js with "Add to PATH" checked, or use the full npx path (see above).

JSON syntax errors

Notepad won't tell you when your JSON is broken. Use VS Code or jsonlint.com to validate.

Skill still not showing after restart

Check Task Manager — Claude Desktop sometimes leaves a background process running after you "close" it. Kill all Claude processes, then reopen fresh.

Then read the logs in %APPDATA%\Claude\logs. In PowerShell: type "$env:AppData\Claude\logs\mcp*.log".

Frequently Asked Questions

Where is the Claude Desktop config file on Windows?

At %APPDATA%\Claude\claude_desktop_config.json. Press Windows+R and type %APPDATA%\Claude to open the folder directly.

Why do I need double backslashes in JSON on Windows?

Backslash is an escape character in JSON. A single \ tells JSON "the next character is special". To represent a literal backslash, you need \\. For npx-based skills using package names, this doesn't matter — no paths involved.

Claude Desktop won't find npx — how do I fix it on Windows?

Run where npx.cmd in Command Prompt to get the full path, then use that as the "command" value. Remember to double every backslash in the JSON string.