Financial Cents MCP vs OpenProject

Financial Cents MCP

The server gives assistants 40 tools over an accounting firm's Financial Cents data, under the user's own permissions and bound to one firm by OAuth. Tool descriptions are detailed and client chat is marked as untrusted. It can send and charge invoices with one undivided scope, and there's no status page, numeric MCP rate limit or readable tool schema.

OpenProject

OpenProject's APIv3 has a public OpenAPI 3.1 document with 320 operations, stable error identifiers and optimistic locking, and the same API ships in the free GPL-3.0 Community edition. No request limits are published, API tokens carry their user's full permissions, and 83 security advisories were published in the last twelve months, 13 rated critical.

Financial Cents MCP

1. Call whoami first and work out date windows from user.timezone, not company.timezone
2. Resolve clients and projects with list_clients or list_projects search, since lookup covers only reference data such as users, tags and service items
3. Check money units per tool. Invoices, payments, proposals and credit memos use integer cents, while time entries and service-item rates use dollars
4. Never retry a successful invoice_actions, proposal_actions or credit-memo create, since a second call can email or charge the client again
5. Get the person's approval before any write, and use preview: true before sending a proposal

OpenProject

1. Send the API token as Authorization: Bearer <token>, or as the Basic auth password with the user name apikey
2. Read the resource first and send its current lockVersion with every PATCH. A stale value returns 409 UpdateConflict
3. POST to the /form endpoint of a work package to learn writable fields and allowed values before creating or updating
4. URL-encode filters as a JSON array, and add pageSize, offset and select to keep work package lists small
5. Run the agent as a dedicated user with a narrow project role, and treat work package text and comments as untrusted input