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Two ways to run it, both free to start. Open mcp.zovo.one/mcp/connect, copy the dunning-letters URL and paste it into any client that takes a URL. It already carries a free token, so there is nothing to install, no account and no header to set. The URL is https://mcp.zovo.one/mcp/dunning-letters/t/<token>. The token is not optional: the bare https://mcp.zovo.one/mcp/dunning-letters connects and lists its tools and then answers every tool call with HTTP 401, so use the link from /mcp/connect or send Authorization: Bearer <token>. Or download dunning-letters.mcpb and double-click it in Claude Desktop.
Chase overdue invoices without losing the thread. Register an unpaid invoice -- client, invoice reference, amount in integer cents, currency, due date -- and the server runs the escalation ladder: reminder 1 (polite, due + 7 days), reminder 2 (firm, with the late fees note, due + 14), and the final notice (before-action wording, due + 21; the gaps are configurable per invoice). For each stage it generates the letter, as Markdown or as a self-contained printable HTML page. It records what you sent and when, lists everything overdue with days late and stage, ages the whole register into current/30/60/90+ buckets, and answers "what do I need to send today". Nothing is emailed or sent anywhere: this server produces the letter text, and sending it is your act.
Built by theluckystrike.
npm publish for @theluckystrike/mcp-dunning-letters is pending, so npx -y @theluckystrike/mcp-dunning-letters returns 404 today. Until then, a clone+build is the working path.
macOS ~/Library/Application Support/Claude/claude_desktop_config.json, Windows %APPDATA%\Claude\claude_desktop_config.json:
{
"mcpServers": {
"dunning-letters": {
"command": "npx",
"args": ["-y", "@theluckystrike/mcp-dunning-letters"]
}
}
}
claude mcp add dunning-letters -- npx -y @theluckystrike/mcp-dunning-letters
~/.cursor/mcp.json (global) or .cursor/mcp.json (project), same entry as Claude Desktop.
| tool | what it does |
|---|---|
invoice_register |
Start chasing an unpaid invoice: client, reference, amount, currency, due date. Returns DUN-YYYY-NNNN and the three escalation dates |
payment_record |
Record money received, full or partial. A part payment lowers what the next letter asks for; covering the balance closes the ladder |
letter_render |
Generate the chase letter for the current stage -- reminder 1, reminder 2 or the final notice -- as Markdown or self-contained printable HTML. Nothing is emailed: you send the text it produces |
letter_sent |
Record that a letter actually went out, with its date, so the ladder advances. Letters go out in order |
overdue_list |
Every unpaid invoice past its due date: days late, outstanding, letters sent, what is due next, worst first |
aging_summary |
The whole register in current/1-30/31-60/61-90/91+ buckets, counts and totals in integer cents, per currency |
chase_today |
The day's chase list: which invoices cross an escalation threshold today, which letter to send each, what falls due next |
invoice_status |
One chased invoice in full: payments, letters, schedule, next action |
invoice_delete |
Delete an invoice entered wrongly. The id is not reissued |
license_status / license_activate |
Free or Pro, and the key |
| Free | Pro | |
|---|---|---|
| Unpaid invoices chased at once | 3 | Unlimited |
| All three letters, both formats | Yes | Yes |
| Aging summary and the day's chase list | Yes | Yes |
| Late fee accrual in the letters | Yes | Yes |
| Payment recording and history | Yes | Yes |
The cap is on how many chases run at once, never on the letters or the aging: three late payers taken from first reminder to final notice is a real chase list, and an invoice that gets paid frees its slot. What is metered is breadth -- a fourth concurrent chase is a collections workload, not a freelancer's month.
Get Pro: https://mcp.zovo.one/buy/dunning-letters -- $19 one-time for this server, or $39 for the bundle.
The ladder is anchored to the due date, not to the last letter, and the two drift apart exactly when chasing is going badly.
The worked chase in test/_client.mjs: USD 1,250.00 due 2026-06-01, gaps 7/14/21, so the letters fall due on 06-08, 06-15 and 06-22 whether or not anything was sent. If reminder 1 actually goes out late -- say 06-20, twelve days after its date -- a previous-letter-anchored ladder would push the final notice to 07-11. This one does not: 06-22 stands, because the client's obligation was fixed by the due date, not by when you got around to writing. Recording a sending moves only which stage is next; it never moves the schedule. The letters are also strictly sequential: an invoice 60 days late with nothing sent is still owed reminder 1, because a final notice that no polite letter preceded reads as a threat, not a chase.
The late fee is measured the same way, once: simple interest, pro-rata on a 30-day month, on the amount outstanding on the day the letter is written, rounded once to the minor unit. On the worked chase that is 125,000 minor units at 2% over 30 days late -- 2,500 exactly -- and after a 50,000 part payment it is 1,500 on the 75,000 that remains, so the final notice asks for 76,500 and no invented figure more.
All data stays local, in ${XDG_DATA_HOME:-~/.local/share}/mcp-servers/dunning-letters/. Two files: invoices.json, counter.json. Nothing is sent anywhere -- no account, no API key, no network call in this server at all -- and the letters are rendered to text for you to send yourself; this server holds no mail credentials and wants none. License keys are verified offline.
Built by theluckystrike. https://github.com/theluckystrike
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Exact config path, entry and caveats: Claude Desktop · Claude Code · Cursor · VS Code · Windsurf · Cline · Claude.ai and Claude Desktop connectors · all clients
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