Getting Started

Manual Setup

Step-by-step config for Cursor, Claude Desktop, and Claude Code.

View as Markdown

Requires Node.js 18+ - see Prerequisites if you need to install it.

Get Your API Key

1

Open Settings

Click your profile in the top-left of app.smallest.ai and select Settings.

Atoms platform profile dropdown showing the Settings option in the left sidebar
Open the settings menu from your profile dropdown
2

Go to API Keys

Click API Keys in the left sidebar, then click Create API Key in the top-right.

Atoms platform API Keys settings page showing existing keys and the Create API Key button
The API Keys page - click Create API Key to generate a new key
3

Name and Create

Give your key a descriptive name (e.g., smallest-mcp) and click Create API Key. Copy and save it - you won’t see it again.

Create New API Key dialog with a name input field and Create API Key button
Enter a name for your API key and click Create

Install

Already have the Python SDK? smallestai mcp prints this config and the claude mcp add command for you, and smallestai mcp run launches the server via npx. The manual steps below do the same thing by hand.

Open (or create) your Cursor MCP config file:

OSPath
Mac / Linux~/.cursor/mcp.json
Windows%USERPROFILE%\.cursor\mcp.json

Paste this config. If you already have other MCP servers, just add the "smallest" entry inside "mcpServers".

1{
2  "mcpServers": {
3    "smallest": {
4      "command": "npx",
5      "args": ["-y", "@developer-smallestai/smallest-mcp-server"],
6      "env": {
7        "ATOMS_API_KEY": "sk_your_api_key_here"
8      }
9    }
10  }
11}

Replace sk_your_api_key_here with your actual API key.

Don’t share your API key or commit it to git.

Restart your editor

Cmd+Shift+P (Mac) or Ctrl+Shift+P (Windows) → Developer: Reload Window

Verify

Go to Cursor Settings → MCP. You should see smallest listed with a green dot.

Open a new chat (make sure you’re in Agent mode, not Ask mode) and type:

List all my agents

You should see your agents listed back. If you do - you’re done!

Troubleshooting

Node.js isn’t installed or isn’t in your PATH. See Prerequisites for installation instructions.

  • Make sure the mcp.json file is valid JSON (no trailing commas)
  • Verify the file is at ~/.cursor/mcp.json (not inside a project folder)
  • Reload the window: Cmd+Shift+P → Developer: Reload Window
  • Check that you copied the full key starting with sk_
  • Generate a new key from app.smallest.ai → Settings → API Keys

Next steps

Head to the Prompt Cookbook - it has copy-paste prompts for everything you can do.