Privacy

avenir-mcp is a program you run yourself, not a service. Its publisher runs no server and receives none of your data. This page describes what the program does on your machine with the data it obtains through YNAB’s API.

Who sees your data

Who	What	Under whose policy
You, on your machine	avenir-mcp while it runs, and its journal	this page
YNAB	your plan, as always: avenir-mcp reads it, and changes it when you confirm, with your own token	YNAB’s privacy policy
Your model provider	the tool results your MCP client sends to its model: accounts, categories, payees, amounts, memos	your provider’s; nobody’s with a local model
The publisher of avenir-mcp	nothing	—

What avenir-mcp handles

• Your YNAB token. Read at start from YNAB_API_KEY, or from the file named by YNAB_API_KEY_FILE. Kept in memory as a secret value, sent only to YNAB’s API over HTTPS, and never logged, printed, returned to the agent or written to disk. It stays where you put it: your MCP client’s configuration, or that file.
• Your plan’s data: accounts, categories, transactions, payees and memos. Fetched from YNAB when a tool needs it, kept in memory so that the next request asks only for what changed, and returned to your agent as tool results. Never written to disk.
• The journal. After each change you confirm, one line of identifiers: which transaction moved from which category to which, and what an undo needs; for a budget change or a move, the amount assigned before and after; for a target, the one to restore. Never a transaction’s amount, a payee or a memo. The file is readable by your user account only.
• Confirmation codes. In memory, single use, valid 10 minutes.
• Logs. On stderr, identifiers and counts only, warnings and errors by default. Where they end up depends on your MCP client.

How it is secured

• Read-only by default. Tools that change your plan exist only when you set AVENIR_MCP_WRITE=1, and each change is previewed and confirmed before it is sent.
• The token is a secret value in the code: printed, logged or in an error, it shows as **********.
• Bank text is data. Payees and memos come from banks and strangers; they are returned as data, never as instructions to the agent.
• The HTTP transport stays on this machine. It listens on 127.0.0.1 by default, and refuses to allow changes without its own token.
• The code is checked on every change: static analysis, secret scanning of the whole history, and an audit of the locked dependencies. See Security.

How long it is kept

Data	Kept
Plan data	while avenir-mcp runs; gone when it stops
Confirmation codes	usable 10 minutes, and gone when avenir-mcp stops; a code holds a fingerprint of the preview, never its content
Journal	until you delete it; avenir-mcp never trims it
Token	where you stored it, until you remove or revoke it

How to erase it

1. Stop avenir-mcp, or quit your MCP client: the plan data in memory is gone.
2. Delete the journal: ~/.local/state/avenir-mcp/journal.jsonl, or the path in AVENIR_MCP_JOURNAL or under XDG_STATE_HOME. You lose the undo history, nothing else.
3. Revoke the token in YNAB’s developer settings, and remove it from your client’s configuration or from its file.
4. Conversations with your agent are kept by your MCP client and your model provider, not by avenir-mcp: delete them there.

Your data at YNAB stays in your YNAB account, under YNAB’s policy.

Nothing else is collected

avenir-mcp has no telemetry, no account and no server. This documentation site sets no cookies and runs no analytics; its fonts are served by the site itself. GitHub, which hosts it, records visitors’ IP addresses for security, under the GitHub Privacy Statement.

Changes to this page

A release that changes what avenir-mcp stores or sends changes this page in the same release, and its changelog says so. Questions: GitHub issues; the legal notice names the publisher.