FreeAgent MCP Server

A Model Context Protocol server for FreeAgent accounting. Gives Claude (or any MCP client) the ability to list bank transactions, explain/approve them with receipts, create expenses, and log mileage.

What access this server requires

FreeAgent

The FreeAgent OAuth credentials grant full access to the connected FreeAgent account. This server uses that access to:

FreeAgent does not offer granular OAuth scopes — authorising an app grants access to all of the above. The server does not delete transactions, invoices, contacts, or any other data.

Email and file sources (external — not provided by this server)

This server has no email tools. For receipt/invoice search to work automatically, connect one or more of the following MCP servers alongside this one:

• Gmail (e.g. mcp__claude_ai_Gmail) — personal email
• Microsoft 365 / Outlook (e.g. mcp__claude_ai_microsoft-365) — business email

When both are connected, Claude will search all of them automatically for matching receipts before asking you to provide a file manually.

Tools

Prerequisites

FreeAgent OAuth credentials

1. Log in to FreeAgent → Settings → Developer API.
2. Create an OAuth application. Set the redirect URI to http://localhost:8080/callback.
3. Note your Client ID and Client Secret.
4. Run the bundled auth command to complete the OAuth flow and save a refresh token to .mcp.json automatically:

npx @oxygenbubbles/freeagent-mcp-server auth

The command prompts for your Client ID and Client Secret, opens the FreeAgent authorization page in your browser, listens for the callback, exchanges the code for a long-lived refresh token, and writes everything to .mcp.json in the current directory. If .mcp.json already exists, it updates just the freeagent entry.

Installation

git clone https://github.com/OxygenBubbles/freeagent-mcp-server.git
cd freeagent-mcp-server
npm install
npm run build

Configuration

All settings are read from environment variables.

Required

Optional

Built-in vendor → category mappings

The server ships with mappings for common vendors (IONOS, OpenAI, Anthropic, AWS, GitHub, Stripe, Google, Microsoft, Zoom, Notion, Dropbox, Slack, Adobe, Netlify, Vercel, Heroku, DigitalOcean, Cloudflare, Fastmail, Mailchimp). Extend via VENDOR_CATEGORIES:

VENDOR_CATEGORIES='{"ACME CORP":"/v2/categories/285","NETFLIX":"/v2/categories/270"}'

Claude Desktop setup

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "freeagent": {
      "command": "node",
      "args": ["/path/to/freeagent-mcp-server/dist/index.js"],
      "env": {
        "FREEAGENT_CLIENT_ID": "...",
        "FREEAGENT_CLIENT_SECRET": "...",
        "FREEAGENT_REFRESH_TOKEN": "..."
      }
    }
  }
}

Usage examples

List my unexplained Starling transactions for April 2026

Approve explanation 12345678 and attach the base64 receipt

Create an expense for the £22.80 IONOS charge on 3 April — here's the PDF: <base64>

Log 24 miles for a coaching session from Wakefield to Ackworth on 10 April

Mileage rates

When ratePence and MILEAGE_RATE_PENCE are both unset, HMRC approved rates apply automatically:

• 45p/mile for the first 10,000 business miles in the tax year
• 25p/mile above 10,000 miles

Pass cumulativeMilesYTD to enable the threshold crossover calculation.

HMRC has adjusted these rates historically. If they change again, override without editing source by setting HMRC_RATE_HIGH_PENCE, HMRC_RATE_LOW_PENCE, and/or HMRC_THRESHOLD_MILES.

Development

npm run dev        # watch mode (tsx)
npm run build      # compile TypeScript → dist/
npm start          # run compiled server
npm test           # run unit tests once
npm run test:watch # watch mode for tests

Claude Code setup

Create .mcp.json in your project directory (or ~/.mcp.json for global access):

{
  "mcpServers": {
    "freeagent": {
      "command": "node",
      "args": ["/path/to/freeagent-mcp-server/dist/index.js"],
      "env": {
        "FREEAGENT_CLIENT_ID": "...",
        "FREEAGENT_CLIENT_SECRET": "...",
        "FREEAGENT_REFRESH_TOKEN": "..."
      }
    }
  }
}

HTTP mode

Set PORT to run as an HTTP server (for webhooks, iPhone Shortcuts, Power Automate):

PORT=3000 AUTH_TOKEN=a-long-random-string node dist/index.js

Always set AUTH_TOKEN when exposing HTTP mode — every request must include Authorization: Bearer <AUTH_TOKEN> or it is rejected with 401. Without AUTH_TOKEN the server starts anyway but prints a warning to stderr and accepts all requests; only do that on a trusted loopback interface.

Security

• Credentials are environment variables, never in code
• FreeAgent tokens are cached in memory and refreshed automatically
• Transactions are never approved without a confirmed receipt or explicit instruction
• The server never creates new categories — only selects from existing ones
• .mcp.json is excluded from git via .gitignore

Licence

MIT