A budgeting app with a built-in MCP server

FireBudget is a zero-based budgeting app for Mac with a built-in MCP server. When you turn it on, an AI agent such as Claude Code or Codex can read your budget, import statements, tidy transactions, and reconcile accounts, all through a small set of tools that run on your own Mac. This page explains what that means, lists every tool, and describes the privacy model in plain terms.

What MCP is

The Model Context Protocol (MCP) is an open standard for connecting AI agents to other software. An app that runs an MCP server describes a set of tools, such as “list accounts” or “import transactions”, and an agent that supports MCP can call those tools when it decides they are useful. The agent does the reasoning. The app decides what is allowed and does the work.

For a budgeting app, this means an agent can work with your real data instead of a copy you pasted into a chat, and the app can enforce its own rules on everything the agent writes.

Why put an MCP server in a budget app

The tedious parts of manual budgeting are reading statements, typing rows, picking categories, and checking that balances agree. Agents are good at the first three. They should not be trusted with the fourth on their own say-so.

FireBudget’s design splits the work accordingly:

• The agent reads PDFs, maps descriptions to payees and categories, and asks you when it is unsure.
• FireBudget validates every ID, detects duplicates with a fixed rule, applies the same transfer and budget rules as the app, and checks balances in integer cents.

FireBudget does no fuzzy matching or guessing of its own. It is a strict, well-described interface, so the behavior is predictable and the agent’s mistakes are caught before they are saved.

The tools FireBudget exposes

There are ten tools. Read tools never change anything.

Tool	What it does
list_ledgers	Lists your budgets, with each budget’s currency.
list_accounts	Lists accounts with their balance and cleared balance.
list_categories	Lists category groups and categories.
list_payees	Lists payees by how often you use them, with the category you last used.
list_transactions	Reads transactions for an account and date range.
import_transactions	Adds up to 500 rows at once, including transfers, with duplicate matching and a dry run.
edit_transactions	Changes payee, category, memo, date, or amount on up to 200 rows, with a before-and-after preview.
create_category	Adds a category to an existing group.
set_cleared	Marks transactions cleared or uncleared, with a preview.
reconcile	Compares the cleared balance with a statement balance and locks transactions only on an exact match.

Guardrails built into the tools

• Preview first. Imports, edits, clearing, and reconciling can all run as a dry run that writes nothing and returns exactly what a real run would do.
• All or nothing. If one row in a batch is invalid, nothing is written, and the error lists every problem.
• Exact matches are reported, not re-created. A row that matches exactly one existing transaction is reported as matched. Uncertain matches are created with a warning, and a commit with warnings is refused until the agent explicitly accepts them. The agent is instructed to ask you first.
• Safety snapshots. FireBudget takes a backup before every import or edit that is saved, which appears in the Backups list in Settings.
• Reconciled rows stay locked unless you explicitly agree to an edit after seeing a warning.
• No deletes. Agents cannot delete transactions, move them between accounts, convert them to transfers, change accounts, or change budgeted amounts.

Privacy model

Agent access is designed to be local and opt-in.

• Off by default. Nothing listens until you turn on agent access in Settings.
• Local only. The server runs inside the FireBudget app on 127.0.0.1. Other devices on your network cannot reach it, and it stops when you quit the app.
• Token protected. Agents need a 256-bit access token, which FireBudget stores in your macOS keychain. All your agents share the one token. Rotating it in Settings disconnects every agent immediately. The token is never logged, backed up, or exported.
• Not reachable from web pages. The server rejects requests that come from a browser, so a website cannot drive it.
• No logging of your data. FireBudget does not log tool arguments, results, or transactions.

There are two honest caveats. First, your agent sends whatever it reads to its AI provider (Anthropic for Claude Code, OpenAI for Codex). That is how agents work, and it is your choice what to ask it to read. Second, the token keeps out other users and devices, not software already running under your own Mac account. Turn access off when you are not using it.

Which agents work

• Claude Code, the command-line tool and the Code tab in the Claude desktop app.
• Codex, the command-line tool, the ChatGPT desktop app, and the IDE extension.
• Any other MCP client that supports Streamable HTTP with a custom Authorization header.

Claude Desktop chat, Cowork, and ChatGPT on the web are not supported yet. They cannot reach a server running on your Mac with a token.

Setup takes a minute: turn on access in Settings, copy the ready-made snippet for your agent, and paste it. The Claude Code statement guide and the Codex categorization guide walk through each.

Other budgeting apps and MCP

FireBudget is not the only option, and the right choice depends on where you want your data to live.

• Monarch Money offers an official MCP connector, in beta as of October 2026. It is a hosted connector for a cloud budgeting service, so it works with web-based agents such as ChatGPT on the web, and your data lives with Monarch.
• YNAB has an official API but no official MCP server. Several community-built MCP servers use that API. YNAB lists them as third-party and does not support them.
• Actual Budget and Lunch Money have community-built MCP servers, not official ones.

The difference with FireBudget is the shape of the connection: the server is part of the app, it runs only on your Mac, and no budget data leaves the Mac except what your agent reads.

What FireBudget does not do

FireBudget runs only on Macs with Apple Silicon (M1 or later). It has no bank sync, no mobile app, and no sync between devices. Agent access is included in the one-time purchase, but the agent itself needs its own plan from Anthropic, OpenAI, or another provider. FireBudget must be open for the agent to connect.