🧠 Mental Models MCP

Make better decisions with AI. 7 proven thinking frameworks, built into Claude.

Most bad decisions come from using the wrong way of thinking: adding effort when you need diagnosis, overthinking when you need action, or arguing when you need structure. Mental Models MCP picks the right framework for your situation, walks you through it step by step with your real numbers, and ends with one clear decision and your next action.

Free and open source. Built by SigmaMax AI Solutions.

🚀 Start here: pick your path

Path 1: Add as a connector (easiest, works on phone too)

1. Open claude.ai in a browser and go to Settings → Connectors → Add custom connector.

2. Name: Mental Models. URL: https://mental-models-mcp.vercel.app/mcp

3. Click Add, then switch it on from the tools menu in a chat.

4. Try: "Help me decide: my leads have dropped for 3 months and I don't know why."

Add it once on the website and it appears in the Claude phone app on the same account. Note: custom connectors may need a paid Claude plan. On a free plan, use Path 2.

Path 2: Skill or instructions (no install)

• As a skill: upload skills/mental-models/SKILL.md in Claude → Settings → Capabilities → Skills.

• As instructions: create a Claude Project and paste the contents of that same file into the project instructions.

Path 3: Local MCP server (Claude Desktop, Claude Code, Antigravity)

Needs Node.js 18+ and Git.

git clone https://github.com/ahsanmassgazal-cmd/mental-models-mcp.git
cd mental-models-mcp
npm install
npm test        # should print: 10/10 recommendation cases passed + All HTTP checks passed

Add it to your MCP config. For Claude Desktop, open the config file:

• Windows: press Win+R, type %APPDATA%\Claude, open claude_desktop_config.json

• Mac: ~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "mental-models": {
      "command": "node",
      "args": ["C:\\Users\\YOU\\mental-models-mcp\\src\\index.js"]
    }
  }
}

Use the real full path to src/index.js. On Windows, double every backslash (\\). If the file already lists other servers, add mental-models inside the existing mcpServers block. Fully quit and reopen Claude Desktop.

Claude Code: claude mcp add mental-models -- node /full/path/to/src/index.js. Antigravity / Cursor: add the same node command and path in the MCP settings.

Make it automatic: add this to your custom instructions:

When I face a decision, a recurring problem or a stressful situation, call recommend_mental_model, then apply_mental_model with the top result, and end with one decision and my next action.

Related MCP server: Waldzell Metagames Server

🧪 Try it: examples

🔧 Tools

❓ Troubleshooting

• Connector fails to add: open the URL in a browser. If you don't see "Mental Models MCP is running", the server is down.

• Tool doesn't appear in Claude Desktop: the config path or JSON is wrong. Check for single backslashes and missing commas, then fully quit and reopen.

• node not recognized: install Node.js LTS, then reopen your terminal.

How it works

Runs locally with simple keyword rules: zero API calls, zero tokens, no data stored. Edit the models in src/models.js and add a case in test/test.js for each change.

Works great together with Model Advisor MCP, which tells you which Claude model to use for each task.

Roadmap

• More models: SWOT, Inversion, Second-Order Thinking, Regret Minimisation, Eisenhower Matrix

• Decision journal: log decisions and review outcomes later

• Team mode for group decisions

License

MIT © SigmaMax AI Solutions

Need AI agents for your business? SigmaMax builds AI agents and automation for companies across the GCC, India and beyond. 🌐 sigmamaxaisolutions.com · ✉️ ahsansigmamaxai@gmail.com · WhatsApp +968 7694 1459