monzo-mcp

MCP server for the Monzo banking API. Read-only access to accounts, balances, pots, transactions, and spending analysis - all through Claude Code or any MCP client.

Unlike other Monzo MCP implementations that use raw bearer tokens (which expire in 6 hours), this server handles full OAuth with automatic token refresh.

Features

• 7 read-only tools - no write operations, no money movement
• OAuth with auto-refresh - tokens refresh automatically, no manual regeneration
• Local transaction cache - SQLite database survives Monzo's 90-day SCA window
• Auto-sync on demand - the cache-reading tools run an incremental sync automatically if the cache wasn't synced today, so you rarely need to call monzo_sync by hand
• Spending analysis - category breakdowns, top merchants, month-over-month comparison
• Transaction search - search by merchant, payee (counterparty), description, or notes across cached history
• Counterparty details - bank transfers (faster payments, p2p, Bacs) are cached with the payee's name, sort code, and account number

Tools

Tool	Description	Data source
monzo_list_accounts	List accounts with types and IDs	Live API
monzo_get_balance	Current balance and spend today	Live API
monzo_list_pots	Savings pots and balances	Live API
monzo_sync	Sync transactions to local cache	Live API -> SQLite
monzo_list_transactions	List/filter cached transactions	Local cache (auto-syncs if stale)
monzo_search_transactions	Search by merchant/payee/description/notes	Local cache (auto-syncs if stale)
monzo_spending	Spending analysis with category breakdown	Local cache (auto-syncs if stale)

Prerequisites

• Python 3.13+
• uv (recommended) or pip
• A Monzo account with an OAuth client registered at developers.monzo.com

Installation

git clone https://github.com/partymola/monzo-mcp.git
cd monzo-mcp
uv venv --python 3.13 .venv
uv pip install -e .

Setup

1. Register a Monzo OAuth client

Go to developers.monzo.com and create an OAuth client:

• Set the redirect URL to http://localhost:6600/callback
• Note your Client ID and Client Secret

2. Authenticate

monzo-mcp auth

This opens your browser for Monzo OAuth. After authorizing, approve the login in your Monzo app within 5 minutes for full transaction history access (Monzo's SCA window).

3. Register with Claude Code

claude mcp add -s user monzo -- /path/to/monzo-mcp/.venv/bin/monzo-mcp

4. First sync

In Claude Code, run monzo_sync to populate the local transaction cache. Do this immediately after auth to take advantage of the SCA window (up to 11 months of history).

CLI

monzo-mcp              Start the MCP server (stdio transport)
monzo-mcp auth         Interactive OAuth setup (opens the browser)
monzo-mcp --version    Print the installed package version

Configuration

All configuration is via environment variables (optional):

Variable	Default	Description
MONZO_MCP_CONFIG_DIR	<package>/config/	Directory for OAuth credentials and tokens
MONZO_MCP_DB_PATH	<package>/monzo.db	Path to SQLite transaction cache

Credential files (created by monzo-mcp auth):

• config/monzo_client.json - OAuth client ID and secret
• config/monzo_tokens.json - Access and refresh tokens (auto-refreshed)

Monzo SCA window

Monzo's Strong Customer Authentication (SCA) limits transaction history access:

• Within 5 minutes of app approval: up to ~11 months of history
• After the window expires: only the last 90 days

The local SQLite cache preserves all synced transactions permanently, so run monzo_sync promptly after monzo-mcp auth.

To backfill a specific range, pass since to monzo_sync - an ISO date (2026-01-01) or datetime (2026-01-01T14:30:00Z). Reaching back more than ~90 days only works inside the SCA window; outside it, only the last 90 days are returned.

Older cached transactions gain fields added in newer versions (e.g. counterparty/payee details on bank transfers) only when re-fetched, which a post-auth full sync does for the history it re-pulls.

Security

• Zero write tools - cannot send money, move funds between pots, or modify transactions
• Monzo API itself cannot send money to external accounts
• Tokens stored as JSON files in the config/ directory (gitignored)
• All API calls are GET requests with Bearer token auth

Troubleshooting

• "SCA required" or only 90 days of history - re-run monzo-mcp auth and approve the login in the Monzo app within 5 minutes, then sync straight away (see the SCA window above).
• Token expired / no refresh - re-run monzo-mcp auth to re-authorise.
• "No transaction data available" - the cache is empty; call monzo_sync (or any cache-reading tool, which auto-syncs) once after authenticating.

Contributing

See CONTRIBUTING.md for development setup, the test workflow, and the pre-commit hook. Changes are tracked in CHANGELOG.md.

License

GPL-3.0-or-later. See LICENSE.