monzo-mcp 1.0.4

Read-only Monzo banking MCP server for Claude Code

Monzo MCP Server for Claude Code

Read-only Monzo banking integration for Claude Code. Query balances, view transactions, check pots, and analyze spending — all through natural conversation.

Features

Tool	Description
monzo_is_authenticated	Verify authentication status (live ping)
monzo_list_accounts	List all accounts (current, joint, flex)
monzo_get_balance	Current balance and today's spending
monzo_list_transactions	Transaction history with merchant details
monzo_get_transaction	Full detail on a single transaction
monzo_list_pots	All pots with balances and goals
monzo_spending_summary	Aggregated spending by category and merchant

Prerequisites

1. Python 3.10+
2. A Monzo developer OAuth client — confidential type
3. Set the redirect URL to http://localhost:3118/callback
4. Claude Code (CLI or VS Code extension)

Why do I need my own OAuth client? Monzo restricts API access to personal use — there's no public app model. You create your own client at developers.monzo.com and only your credentials touch this server.

---

Quick Start

1. Create an OAuth Client

Go to developers.monzo.com and create a Confidential client.

• Redirect URL: http://localhost:3118/callback

2. Installation Options

Option 1: Claude Code Plugin (Marketplace)

/plugin marketplace add tcoretech/monzo-mcp
/plugin install monzo@tcoretech

Option 2: uvx (recommended — no clone needed)

claude mcp add monzo \
  -e MONZO_CLIENT_ID=your_client_id \
  -e MONZO_CLIENT_SECRET=your_client_secret \
  -- uvx --from monzo-mcp monzo-mcp

Option 3: pip install

pip install monzo-mcp
claude mcp add monzo \
  -e MONZO_CLIENT_ID=your_client_id \
  -e MONZO_CLIENT_SECRET=your_client_secret \
  -- monzo-mcp

Option 4: Clone & Run from Source

git clone https://github.com/tcoretech/monzo-mcp.git
cd monzo-mcp
pip install -e .
claude mcp add monzo \
  -e MONZO_CLIENT_ID=your_client_id \
  -e MONZO_CLIENT_SECRET=your_client_secret \
  -- python3 mcp-server/server.py

3. Generic MCP Configuration (Desktop/JSON)

For use with Claude Desktop or other MCP clients, add this to your configuration:

{
  "mcpServers": {
    "monzo": {
      "command": "python3",
      "args": [
        "/absolute/path/to/monzo-mcp/mcp-server/server.py"
      ],
      "env": {
        "MONZO_CLIENT_ID": "YOUR_CLIENT_ID",
        "MONZO_CLIENT_SECRET": "YOUR_CLIENT_SECRET",
        "MONZO_REDIRECT_URI": "http://localhost:3118/callback"
      }
    }
  }
}

---

Authentication (Seamless OAuth)

This server implements a Seamless Loopback Flow. You don't need to run a separate setup command.

1. Just-in-Time Auth: When you first ask Claude about your Monzo account, the server will detect missing tokens and automatically open your browser to the Monzo login page.
2. Loopback Listener: A temporary local server (defaulting to port 3118) catches the callback from Monzo and saves your tokens securely to ~/.monzo-mcp/tokens.json.
3. WSL & Docker Support: The server is environment-aware and will use PowerShell to bridge to your Windows host browser if running in WSL.
4. SCA (Strong Customer Authentication): If Monzo requires an app approval, Claude will inform you. Simply tap "Approve" in your Monzo mobile app and tell Claude you've done so.

Note: Tokens are stored with 0600 permissions (owner only). Access tokens are refreshed automatically.

Where are tokens stored?

~/.monzo-mcp/tokens.json    # access_token, refresh_token, account_id

This file is created automatically, permissions restricted to your user, and never needs manual editing. Delete it to force re-authentication.

---

Usage Examples

Once connected, ask Claude things like:

• "What's my Monzo balance?"
• "Show my last 20 transactions"
• "How much did I spend on eating out this month?"
• "Give me a spending summary for the last 30 days"
• "What are my pot balances?"
• "Show transactions from Tesco last week"

---

Architecture

monzo-mcp/
├── .claude-plugin/          # Plugin metadata for marketplace
│   ├── plugin.json
│   └── marketplace.json
├── mcp-server/              # MCP server (Python)
│   ├── server.py            # FastMCP entry point (stdio)
│   ├── tools.py             # 7 read-only tool definitions
│   ├── monzo_client.py      # Async API client with retry
│   ├── auth.py              # OAuth token management, loopback listener, auto-refresh
│   └── .env.example
├── skills/monzo/
│   ├── SKILL.md             # Domain knowledge for Claude
│   └── monzo-api-reference.md
├── pyproject.toml           # Python packaging (pip/uvx)
├── LICENSE
└── README.md

Credential flow:

User provides                 Server handles internally
┌──────────────────┐         ┌──────────────────────────┐
│ MONZO_CLIENT_ID  │──env──▶ │ OAuth browser flow       │
│ MONZO_CLIENT_SECRET│       │ Token exchange            │
└──────────────────┘         │ Token refresh             │
                             │ Account auto-detection    │
                             │ ~/.monzo-mcp/tokens.json  │
                             └──────────────────────────┘

Security:

• Read-only — no write operations, no fund transfers
• Credentials stored locally only, never transmitted beyond the Monzo API
• Token file restricted to user permissions (0600)
• Automatic token refresh on expiry
• Exponential backoff on rate limits

Important Notes

• 90-day limit: Due to Monzo's Strong Customer Authentication (SCA), transaction history is limited to 90 days unless you re-authenticate within 5 minutes in the Monzo app.
• Personal use only: The Monzo API is restricted to personal use — Monzo does not allow public applications.
• Rate limits: Monzo enforces rate limits. The client handles retries automatically.
• Amounts: All API amounts are in minor units (pence for GBP). Claude converts to pounds.

License

MIT