YNAB Assistant

A FastMCP server that lets AI assistants interact with your YNAB budget through the Model Context Protocol.

What is this?

This is a personal MCP server that exposes YNAB API functionality as tools that Claude (or other AI assistants) can use. It lets you ask questions about your budget, create transactions, update categories, and more using natural language.

Setup

1. Install dependencies:

   uv sync

2. Set your YNAB access token:

   Get your token from YNAB Developer Settings, then:

   export YNAB_ACCESS_TOKEN="your_token_here"

   Or use direnv with .envrc:

   echo 'export YNAB_ACCESS_TOKEN="your_token_here"' > .envrc direnv allow

3. Run the server:

   uv run python main.py

   Server runs at http://localhost:8000/mcp

What can it do?

The server provides 21 tools across different areas:

• Accounts: List accounts, get account details

• Categories: View and update category budgets and notes

• Transactions: Create, read, update, and delete transactions

• Months: View budget month details

• User: Get authenticated user info

Development

Run linters until clean:

Notes

• All amounts in YNAB are in "milliunits" (e.g., -50000 = -$50.00)

• Most tools default to your last-used budget for convenience

• Built with FastMCP and the YNAB SDK