MCP for YNAB
A fast, safe MCP server for YNAB — full budget access for Claude and other AI assistants, read-only by default.
35 tools covering budgets, transactions, categories, payees, accounts, scheduled transactions, and server-computed analytics (spending summaries, budget health, recurring charges, income vs. expense, net worth, month-close coverage, category and credit-card float history). Writes are off unless you explicitly turn them on, risky writes require confirmation, and writes that edit or delete existing data can be undone.
Install
There are two ways to run Cove for YNAB: local (the npm package, one client at a time) or
remote (one URL + token, works from Desktop, Code, and mobile identically).
Install (local)
Runs on your machine via npx. Works with Claude Code and Claude Desktop. Not reachable from
mobile — mobile clients need the remote path below.
Claude Code:
claude mcp add ynab -e YNAB_ACCESS_TOKEN=xxx -- npx -y @walensis/cove-mcp
Claude Desktop — add this to your config (claude_desktop_config.json):
{
"mcpServers": {
"cove": {
"command": "npx",
"args": ["-y", "@walensis/cove-mcp"],
"env": {
"YNAB_ACCESS_TOKEN": "xxx"
}
}
}
}
Replace xxx with your personal access token (see Getting a token below). By
default the server is read-only; add "YNAB_ALLOW_WRITES": "1" to env (or export it in Claude
Code's -e) once you want the write tools — see Read-only by default.
Any other client that speaks MCP over stdio can run the server the same way:
npx -y @walensis/cove-mcp
with YNAB_ACCESS_TOKEN set in its environment.
Install (remote)
One URL and a token, and it works identically from Claude Desktop, Claude Code, and claude.ai on
mobile — no local process to keep running. This is apps/worker, a single-tenant Cloudflare
Worker you deploy on your own account, with your own YNAB token: apps/worker/README.md
has the full deploy runbook and how to point each kind of client at it.
The model, in short: everything in this repo — the engine, the stdio server, and this remote
endpoint — is open source and free, and it's a Tool: stateless, answers when asked, does nothing on
its own. Anything autonomous or metered — always-on float monitoring, digests, LLM-written
narratives, the browser extension — is a Product, and lives in a separate hosted offering we run
and charge for. Self-hosting this worker gets you the Tool half for free, forever; it does not
include the always-on half. If you'd rather build that yourself on top of the same open engine,
see docs/build-your-own-monitoring.md.
Getting a token
- Go to app.ynab.com and sign in.
- Open Account Settings → Developer Settings.
- Under Personal Access Tokens, click New Token, confirm your password, and copy the token.
- Use that value as
YNAB_ACCESS_TOKEN. Treat it like a password — anyone with it has full access to your budget for as long as it's valid.
If you'd rather not put the token directly in your MCP client config, set YNAB_ACCESS_TOKEN_FILE to the path of a file containing just the token instead.
Read-only by default, writes are opt-in
By default this server only exposes read tools — nothing it does can change your budget. To enable the write tools (creating/editing/deleting transactions, assigning money, etc.), set:
in the server's environment and restart it. With writes enabled:
- Confirmation gates: destructive or bulk operations (deleting a transaction, deleting a scheduled transaction, bulk-updating more than 5 transactions) require an explicit
confirm: true — and bulk updates also require expected_count to match the number of rows — so the assistant has to show you what it's about to do before it does it.
- Undo: writes that change existing data — transaction edits/deletes, category edits, budget assignments/moves, scheduled transaction edits/deletes, payee renames — are journaled locally, and the
undo_last tool reverses the most recent one (up to 50 writes of history, stored in ~/.cove/undo.json). Writes that create something (create_category, create_payee, create_account) and import_transactions are not reversible — YNAB's API has no delete for categories, payees, or accounts, and no way to undo an import. Those are still journaled (so undo history stays in order), but undo_last will tell you a given entry can't be undone and move on to the write before it. See PRIVACY.md for details on that file.
Rate limits
The underlying API allows 200 requests/hour per token, shared across every app using that same token (this server, the mobile and web apps for YNAB, other integrations, etc.). This server tracks its own usage client-side and stops itself at 190 requests/hour to leave headroom for the rest of your apps, and prefers small, server-computed responses (aggregates, summaries) over dumping raw rows where it can.
| Tool | Type | Description |
|---|
list_plans | read | List all budgets (plans): id, name, currency, last modified. |
get_plan_overview | read | Orient in one call: accounts, current-month Ready to Assign, age of money, category totals. |
get_month | read | Full detail for one month: Ready to Assign, age of money, every category's status. |
list_transactions | read | List or aggregate transactions with filters, pagination, and field selection. |
get_transaction | read | Full detail for one transaction, including split subtransactions. |
create_transactions | write | Create one or more transactions in bulk, with splits and import dedup. |
update_transactions | write | Bulk edit transactions: categorize, approve, set cleared, edit fields. |
delete_transaction | write | Delete one transaction. Requires confirmation. |
import_transactions | write | Trigger import of linked-account transactions. |
list_scheduled_transactions | read | All scheduled (upcoming/recurring) transactions. |
create_scheduled_transaction | write | Create a scheduled transaction (upcoming bill or recurring income). |
update_scheduled_transaction | write | Update a scheduled transaction. |
delete_scheduled_transaction | write | Delete a scheduled transaction. Requires confirmation. |
list_categories | read | All visible categories with balances and target status. |
create_category | write | Create a category (and its group, if needed). |
update_category | write | Rename or hide a category, or set its target. |
assign_budget | write | Set a category's assigned amount for a month. |
move_money | write | Move assigned money between two categories in a month, atomically. |
list_payees | read | All payees (id, name, transfer flag). |
rename_payee | write | Rename a payee across all its transactions. |
create_payee | write | Create a payee. |
create_account | write | Create an account, with a starting balance. |
spending_summary | read | Server-computed spending by category or payee, with optional period comparison. |
budget_health | read | Current-month health check: overspending, underfunded targets, credit-card float. |
detect_recurring_charges | read | Find recurring charges (subscriptions/bills) from about 13 months of history. |
income_vs_expense | read | Monthly income/expense/net series. |
net_worth_history | read | Monthly net-worth series computed from full transaction history. |
month_close | read | Month-close report for a cutoff date: credit-card coverage, blockers, overspent categories, ranked donors. |
propose_coverage | read | Ordered move proposals to bring every overspent category to zero for the cutoff month. |
get_category_history | read | One category's monthly series (assigned/activity/available) across a month range. |
credit_card_float_history | read | Per-month credit-card float analysis over a range: owed vs. payment-category available, gap, changed flag. |
backfill_ledger | local write | Backfill the local balance-forward ledger from history: one record per card per fully-elapsed month, with causes and the discovery summary ("carrying $X since "). Local file only (~/.cove/ledger.json) — never touches YNAB. |
record_month_close | local write | Persist a month-close balance-forward record (per-card gaps, blockers, causes, applied moves). Local file only (~/.cove/ledger.json) — never touches YNAB. |
get_month_close_ledger | read | Read past balance-forward records (newest first), optionally filtered by cutoff. |
undo_last | write | Undo the most recent write made through this server. |
The month-close session
A guided monthly catch-up flow (Balance → Plan) built on top of the tools above: it works
through blockers until the coverage gap is trusted, attributes credit-card float changes to
their cause, proposes donor-first coverage moves, and — once you approve them — writes a
balance-forward record via record_month_close so next month's session has a baseline to
compare against (get_month_close_ledger). On the very first run, the ledger is empty — the
session runs backfill_ledger for each card first and leads with what it finds (e.g.
"carrying $865.75 since 2024-08") before attributing anything further.
- Claude Code: use the
/month-close skill.
- Claude Desktop and other MCP clients: the server exposes the same flow as the
month-close-session MCP prompt.
- Full walkthrough: docs/playbooks/month-close.md.
Remote MCP endpoint (self-host)
The remote worker (see Install (remote) above) exposes the same 35 tools over a
token-authenticated remote MCP endpoint — a bearer-header route for header-capable clients, plus a
token-in-path route so claude.ai's URL-only custom connectors can reach your budget directly —
built on the same library entrypoint this package exports for embedding:
import { tools, buildServer } from '@walensis/cove-mcp'
It does not include always-on monitoring — that's a separate, hosted product. See
docs/build-your-own-monitoring.md if you want to build that
yourself on top of the same open attribution engine.
Full deploy runbook: apps/worker/README.md.
Development
This is a pnpm monorepo: packages/core (@walensis/cove-core, the API client for YNAB and domain logic) and apps/mcp (@walensis/cove-mcp, the MCP server that wraps it).
Naming: Cove is the product; @walensis/cove-core is the engine, @walensis/cove-mcp is the MCP surface, and the MCP registry entry keeps its descriptive mcp-for-ynab name for discoverability.
pnpm install
pnpm build
pnpm test
pnpm typecheck
To smoke-test against a real budget (read-only — it never writes):
YNAB_ACCESS_TOKEN=xxx pnpm smoke
To validate credit_card_float_history against known-good fixture values (read-only):
YNAB_ACCESS_TOKEN=xxx pnpm validate:fixtures
Disclaimer
We are not affiliated, associated, or in any way officially connected with YNAB, or any of its subsidiaries or its affiliates.
License
MIT © walensis-labs