— Annex · Tools of the Trade —
Mercurius
A private accounting tool. Built in-house. Operated by JM Woody van Horn on behalf of WvH Hospitality clients.
What This Is
Mercurius, a WvH Hospitality LLC AI Agent, is a forty-seven-tool Model Context Protocol (MCP) server that allows Claude (Anthropic's AI assistant) to read from and write to QuickBooks Online on behalf of an authorized accountant. It runs locally, on a single MacBook, in Mentone, California.
It is not a product. It is not for sale. It is the in-house bookkeeping instrument of a single fractional-CFO practice, used daily on a small roster of clients who have signed an engagement letter authorizing such access.
Who Operates It
WvH Hospitality LLC, a California limited liability company (Est. 2017), acting through its Managing Member, JM Woody van Horn. Mailing address: 1947 Garnet St, Mentone, CA 92359. The bot runs only on the Managing Member's own machine. There is no shared instance, no hosted version, no SaaS.
How It Works
- Each client realm is connected via Intuit's standard OAuth 2.0 consent flow. The realm-owner (the WvH client) authorizes access explicitly in QuickBooks.
- OAuth refresh tokens are stored in the operator's macOS Keychain — encrypted at rest by Apple's Data Protection.
- Every read and every write is logged to a local JSONL audit file (
~/.qbo-mcp-audit.jsonl) with timestamp, environment, realm ID, tool name, and request hash. The audit log is part of the client's engagement file. - High-value writes (≥ $10,000) require an explicit confirmation flag. Duplicate invoice and bill numbers are refused before they reach QBO.
- Writes that QBO supports for idempotency use Intuit's native
requestidparameter, derived from a stable hash of the request body, to make accidental retries safe.
If You Arrived Here From Intuit
If QuickBooks redirected you to this page during an OAuth consent screen and you are not a WvH Hospitality client, you can safely close this tab — there is nothing for you to do here. This bot only operates against realms it has been explicitly authorized for by their owners, under written engagement.
If you are a WvH client and you have questions about what the bot reads or writes in your books, please reach out at me@wvhhospitality.com.
The Documents
- Privacy Policy — what data is touched, where it lives, who else sees it.
- End-User License Agreement — the terms of use between operator and realm-owner.
- After Disconnection — what happens when access is revoked.