Firefly III MCP Server

A Model Context Protocol (MCP) server that provides programmatic access to Firefly III personal finance management through Claude Desktop, Cursor IDE, and other MCP-compatible AI assistants.

📚 Documentation

📖 Full Documentation

Related MCP server: YNAB MCP Server

Overview

This MCP server enables AI assistants to interact with your Firefly III instance, allowing you to manage your personal finances through natural language conversations. You can:

• 💰 Manage accounts: List, create, update, and delete asset, expense, revenue, and liability accounts

• 📊 Handle transactions: Create, retrieve, update, and delete financial transactions

• 💳 Budget management: Work with budgets, budget limits, and track spending

• 🏷️ Categorization: Manage transaction categories and tags

• 💸 Bill tracking: Handle recurring bills and payment monitoring

• 🐷 Piggy banks: Manage savings goals and track progress

• ⚙️ Rules & automation: Configure transaction rules and rule groups

Key Features

• 🤖 AI Integration: Works seamlessly with Claude Desktop, Cursor IDE, and other MCP clients

• 💡 Comprehensive API: Supports most Firefly III v1 API endpoints

• ⚡ Flexible modes: Choose between consolidated tools or direct API access

• 🔒 Type-safe: Full Pydantic model validation for all requests/responses

• 🎯 Configurable: Enable only the Firefly III entities you need

Quick Example

Once set up, you can interact with your finances naturally:

"Show me my account balances"
"Create a new expense for $25.50 at Coffee Shop from my Checking Account"
"What's my budget status for this month?"
"List all my transactions from last week"
"Create a new savings goal for a vacation with a target of $2000"
"Show me all bills that are due this month"
"Help me create a transaction rule that automatically categorizes Starbucks purchases as 'Coffee'"
"Create a new budget category for 'Home Improvement' with a $500 monthly limit"

Requirements

• Python 3.12+

• A running Firefly III instance

• Firefly III API token (Personal Access Token)

🚀 Quick Setup

Local Installation

Clone and set up the project locally:

# Clone the repository
git clone https://github.com/horsfallnathan/firefly-iii-mcp-server.git firefly-mcp
cd firefly-mcp

# Install with UV (recommended)
uv sync

# Or with pip
python -m venv .venv
source .venv/bin/activate  # On Windows: .venv\Scripts\activate
pip install -e .

Configuration

Create a .env file in the project root:

# Required: Your Firefly III API URL and token
FIREFLY_API_URL=https://your-firefly-instance.com/api/v1
FIREFLY_API_TOKEN=your_token_here

# Optional: Enable all entities (default: just accounts). Requires `FIREFLY_DIRECT_MODE=true`
# Enabling all entities would lead to about 76 tools being registered and most clients suggest a maximum of 40 tools
FIREFLY_ENABLED_ENTITIES=all

# When false, the server will register consolidated tools for dynamic operation. When true, it will register individual tools for each operation
FIREFLY_DIRECT_MODE=false

FIREFLY_LOG_LEVEL=INFO

🔑 Getting a Firefly III API Token:

1. Log into your Firefly III instance

2. Go to Options → Profile → OAuth

3. Click Create New Token

4. Give it a descriptive name (e.g., "MCP Server")

5. Copy the generated token to your .env file

📖 See full configuration guide

🔌 MCP Client Integration

Cursor IDE

Add to your workspace or global settings:

{
  "mcp.servers": {
    "firefly-mcp": {
      "command": "uv",
      "args": ["--directory", "/absolute/path/to/firefly-mcp", "run", "firefly-mcp"],
      "env": {
        "FIREFLY_API_URL": "https://your-firefly-instance.com/api/v1",
        "FIREFLY_API_TOKEN": "your_token_here",
        "FIREFLY_ENABLED_ENTITIES": "all",
        "FIREFLY_DIRECT_MODE": "false"
      }
    }
  }
}

VSCode

Create an mcp.json file in your project root or workspace:

{
  "servers": {
    "firefly-mcp": {
      "command": "uv",
      "args": ["--directory", "/absolute/path/to/firefly-mcp", "run", "firefly-mcp"],
      "env": {
        "FIREFLY_API_URL": "https://your-firefly-instance.com/api/v1",
        "FIREFLY_API_TOKEN": "your_token_here",
        "FIREFLY_ENABLED_ENTITIES": "all",
        "FIREFLY_DIRECT_MODE": "false"
      }
    }
  }
}

Operation Modes

Consolidated Mode (Default)

Provides three meta-tools for dynamic operation:

• firefly_execute(entity, operation, params) - Execute any Firefly III operation

• firefly_list_operations(entity?) - List available operations

• firefly_get_schema(entity, operation) - Get parameter schema for operations

Direct Mode

Set FIREFLY_DIRECT_MODE=true to register individual tools for each operation:

• account_list(limit?, page?) - List accounts

• account_get(id) - Get account details

• transaction_create(transactions) - Create transactions

• And many more...

🛠️ Development & Testing

Using MCP Inspector

For development and debugging, use the MCP Inspector:

# Install and run MCP Inspector
npx @modelcontextprotocol/inspector uv run firefly-mcp

The MCP Inspector provides a web interface where you can:

• 🧪 Test all available tools and operations

• 🔍 Inspect request/response schemas

• 🐛 Debug server connectivity and authentication

• ✅ Validate your Firefly III configuration

📖 See full development guide

Running Tests

# Run all tests
make test-all

# Run with coverage
make coverage

# Run specific test types
make test-unit
make test-integration

Local Development

# Development with .env file
make dev

# Direct execution
uv run firefly-mcp
python -m firefly_mcp.main

📋 Environment Variables Reference

🎯 API Compatibility

This MCP server is compatible with Firefly III API v1. It has been tested with:

• ✅ Firefly III v6.x

🤝 Contributing

1. Fork the repository

2. Create a feature branch

3. Make your changes

4. Add tests for new functionality

5. Run the test suite

6. Submit a pull request

📄 License

This project is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0). See the LICENSE file for details.