Expense Tracker MCP Server

A local Model Context Protocol (MCP) server that helps you track grocery and shopping expenses by parsing PDF receipts, automatically categorizing items, and storing them in a SQLite database for easy querying.

Features

• PDF Receipt Parsing: Extract line items, prices, and metadata from PDF receipts

• Smart Categorization: Hybrid approach using static rules + LLM fallback for item classification

• SQLite Storage: Persistent local database for all your expense data

• Query Tools: Ask questions like "When did I last buy milk?" or "How often do I buy bread?"

• Multi-Store Support: Works with receipts from Walmart, Costco, Target, and more

Installation

Prerequisites

• Python 3.11 or higher

• uv (recommended) or pip

Step 1: Clone or Download

cd /Users/sharan/Desktop/expense_tracker_mcp

Step 2: Install Dependencies

Using uv (recommended):

uv sync

Using pip:

pip install -r requirements.txt

Step 3: Initialize Database

The database is automatically initialized when you first run the server. The SQLite database will be created at data/expenses.db.

Running Locally

To test the server locally:

python main.py

or with uv:

uv run main.py

The server will start and listen on stdin/stdout (MCP protocol).

Connecting to Claude Desktop

Step 1: Locate Claude Desktop Config

The configuration file is located at:

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

• Windows: %APPDATA%/Claude/claude_desktop_config.json

• Linux: ~/.config/Claude/claude_desktop_config.json

Step 2: Add MCP Server Configuration

Edit the config file and add this entry to mcpServers:

{
  "mcpServers": {
    "expense-tracker": {
      "command": "uv",
      "args": [
        "--directory",
        "/Users/sharan/Desktop/expense_tracker_mcp",
        "run",
        "main.py"
      ]
    }
  }
}

Alternative (using python directly):

{
  "mcpServers": {
    "expense-tracker": {
      "command": "/Users/sharan/Desktop/expense_tracker_mcp/.venv/bin/python",
      "args": [
        "/Users/sharan/Desktop/expense_tracker_mcp/main.py"
      ]
    }
  }
}

Step 3: Restart Claude Desktop

After saving the config, restart Claude Desktop to load the MCP server.

Usage

Once connected to Claude Desktop, you can use these tools:

1. Import a Receipt

Upload a PDF receipt and the server will parse it:

Import this receipt: /path/to/walmart_receipt.pdf

Example Response:

{
  "status": "success",
  "receipt_id": 1,
  "store_name": "Walmart",
  "purchase_date": "2025-01-15",
  "total": 45.67,
  "items_count": 12,
  "item_types": {
    "milk": 1,
    "bread": 1,
    "eggs": 1,
    "veggies": 3,
    "snacks": 2,
    "beverages": 2,
    "meat": 2
  }
}

2. Query Item History

Ask when you last bought something:

When did I last buy milk?

or

Show me all my milk purchases in the last 6 months

Example Response:

{
  "item_type": "milk",
  "purchases": [
    {
      "date": "2025-01-15",
      "store": "Walmart",
      "item_name": "Organic Milk 2%",
      "quantity": 1.0,
      "price": 4.99
    },
    {
      "date": "2024-12-28",
      "store": "Costco",
      "item_name": "Kirkland Milk",
      "quantity": 2.0,
      "price": 6.99
    }
  ],
  "stats": {
    "total_purchases": 2,
    "last_purchase_date": "2025-01-15",
    "first_purchase_date": "2024-12-28",
    "average_days_between": 18.0,
    "total_spent": 11.98
  }
}

3. List All Categories

See all item types you've purchased:

What categories of items have I bought?

Example Response:

{
  "item_types": [
    {
      "item_type": "milk",
      "total_purchases": 12,
      "last_purchase_date": "2025-01-15",
      "total_spent": 59.88
    },
    {
      "item_type": "bread",
      "total_purchases": 8,
      "last_purchase_date": "2025-01-10",
      "total_spent": 27.92
    }
  ],
  "total_categories": 15
}

Supported Item Categories

The categorizer recognizes these item types out of the box:

Dairy: milk, oatmilk, eggs, cheese, yogurt, butter

Grains: bread, rice, lentils, pasta, cereal

Produce: veggies, fruits, potatoes

Proteins: meat, fish

Snacks & Beverages: snacks, beverages

Pantry: oil, spices, sauce

Household: cleaning, paper

Fallback: other (for unrecognized items)

Adding New Categories

Edit expense_tracker/categorizer.py and add patterns to the ITEM_TYPE_MAPPINGS dictionary:

ITEM_TYPE_MAPPINGS = {
    # ... existing categories ...
    "tofu": ["tofu", "bean curd", "soy protein"],
}

Database Schema

The SQLite database (data/expenses.db) contains two main tables:

receipts

• id: Auto-increment primary key

• store_name: Store name (e.g., "Walmart")

• purchase_date: ISO format date (YYYY-MM-DD)

• subtotal: Subtotal amount (nullable)

• tax: Tax amount (nullable)

• total: Total amount (required)

• created_at: Timestamp

items

• id: Auto-increment primary key

• receipt_id: Foreign key to receipts table

• item_name_raw: Original item name from receipt

• item_type: Normalized category

• quantity: Item quantity (default: 1.0)

• unit_price: Price per unit (nullable)

• line_total: Total price for this line

• created_at: Timestamp

How It Works

1. PDF Parsing

Uses pdfplumber to extract text from PDF files, then applies regex patterns to identify:

• Store name (Walmart, Costco, Target, etc.)

• Purchase date (multiple date formats supported)

• Line items with quantities and prices

• Totals (subtotal, tax, total)

2. Item Categorization

Hybrid approach:

1. Static Rules (fast, deterministic)

   • Checks item name against pre-defined patterns

   • Handles common grocery items with keyword matching

   • ~90% accuracy for typical grocery items

2. LLM Fallback (smart, adaptive)

   • Uses Claude via FastMCP's Context.sample() for unknown items

   • Provides better accuracy for unusual or new items

   • Automatically adapts to items not in static mappings

3. Database Storage

All data is stored in a local SQLite database with proper indexing for fast queries:

• Indexes on purchase_date, store_name, item_type

• Foreign key constraints for data integrity

• Support for aggregate queries and statistics

Troubleshooting

Server not appearing in Claude Desktop

1. Check that the path in claude_desktop_config.json is correct

2. Restart Claude Desktop completely

3. Check Claude Desktop logs for errors

PDF parsing errors

• Ensure the PDF is text-based (not a scanned image)

• Try opening the PDF in a viewer to verify it contains selectable text

• Check that the file path is absolute, not relative

Database locked errors

• Close any other tools accessing data/expenses.db

• Make sure only one instance of the server is running

Development

Running Tests

pytest tests/

Adding New Features

The modular architecture makes it easy to extend:

• New categorization rules: Edit expense_tracker/categorizer.py

• New receipt formats: Update patterns in expense_tracker/pdf_parser.py

• New MCP tools: Add tool functions to main.py with @mcp.tool decorator

• Database changes: Modify schema in expense_tracker/database.py

License

MIT License - feel free to use and modify for your needs.

Contributing

Contributions welcome! Areas for improvement:

• Support for more receipt formats

• Better item categorization rules

• Export to CSV/Excel functionality

• Visualization dashboards

• Multi-user support

Support

For issues or questions:

• Check the FastMCP documentation

• Review MCP protocol docs

• File an issue on GitHub

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