Scribo Skill

Free, AI-native e-invoicing — from Claude, ChatGPT & Codex.

Contents

• What is Scribo?
• What is the Scribo skill?
  • Demo
• Getting started
  • Quickstart
  • Setup & prerequisites
• Usage
  • How it works
  • Examples
• Compliance
• FAQ
• Resources
• License

What is Scribo?

Scribo is a free, conversational e-invoicing tool. Describe an invoice in plain language — "bill Acme GmbH €2,400 for May design work" — and it drafts a structured invoice for you to review, download and send directly.

Just ask your AI agent about Scribo: it ships as an MCP server, a CLI, and a Claude/Codex skill, alongside a public HTTP API and a web app. Free forever — no credit card. You just need a sender email.

Built by Causa Prima — Scribo is built by Causa Prima, a company building agentic AI for the CFO office. It's our first freely available skill — an early glimpse of what we're building.

What is the Scribo skill?

The Scribo skill teaches your AI assistant to create invoices for you. Add it once, then just ask — "draft an invoice for 3 days of consulting at €1,200/day" — and your assistant gathers the details and hands back a finished, compliant invoice in the chat, ready to download and send. No new app to learn, no forms to fill in.

It works wherever you already work: Claude (Claude.ai, Claude Code, Claude Desktop), ChatGPT, and the OpenAI Codex CLI. Free, no signup — your email is all you need.

Demo

https://github.com/user-attachments/assets/b6603478-4702-4941-bf01-bf4c04bbb098

Getting started

Quickstart

If you use Claude Code, you're two commands away:

/plugin marketplace add causa-prima-ai/scribo-skill
/plugin install scribo-skill@scribo-skill

Then just ask:

Draft an invoice from Example GmbH to Acme GmbH for 3 days of consulting at €1,200/day, 19% VAT.

The skill triggers automatically, asks for anything it's missing, verifies your sender email once (a 6-digit code arrives by email), and returns a downloadable invoice.

On Claude.ai, Claude Desktop, ChatGPT, or Codex CLI instead? Use the matching install method below.

Setup & prerequisites

Prerequisites. Hosted assistants (Claude.ai, Claude Desktop, ChatGPT) need nothing installed. For local installs (Claude Code, Codex CLI) you'll need bash 4+, curl, and jq on your machine (openssl optional).

Pick the method that matches how you run your assistant:

Plugin install — Claude Code

/plugin marketplace add causa-prima-ai/scribo-skill
/plugin install scribo-skill@scribo-skill

The skill activates as /scribo-skill:scribo and triggers automatically when you ask to draft an invoice.

.zip upload — Claude.ai, Claude Desktop, ChatGPT

1. Download scribo-skill.zip from the latest release.
2. Upload it:
   • Claude.ai / Claude Desktop — Settings → Customize → Skills → Upload skill.
   • ChatGPT — New skill → Upload from your computer.

One upload covers new chats on that account.

git clone — Codex CLI, manual Claude Code

Clone once, then copy the inner skills/scribo folder into your assistant's skills directory:

git clone https://github.com/causa-prima-ai/scribo-skill /tmp/scribo-skill
cp -r /tmp/scribo-skill/skills/scribo ~/.codex/skills/scribo     # Codex CLI
# or  .claude/skills/scribo     (Claude Code — this project)
# or  ~/.claude/skills/scribo   (Claude Code — all projects)

SKILL.md must end up at …/scribo/SKILL.md. Restart your assistant afterward.

Verify. Ask your assistant: "list the jurisdictions Scribo supports." You should get back a list of supported countries.

Full install detail (Cowork, team installs, troubleshooting): scribo.causaprima.ai/docs/skill.

Usage

How it works

You don't fill in a form — you describe the invoice and your assistant does the rest. When you ask for an invoice, it:

1. Gathers the details in a short back-and-forth — who's billing (your business name, address, tax/VAT ID, and the email the invoice is sent from), who's being billed (their name, address, and billing email), and the line items, amounts, and currency.
2. Confirms the tax treatment with you — standard-rated, reverse-charge, exempt, and so on. Scribo never guesses your VAT category; you decide.
3. Verifies your email once. The first time you invoice from a new sender address, Scribo emails a 6-digit code that you paste back to confirm the address is yours. It's reused for ~30 minutes, so you're not asked again on every invoice.
4. Generates and validates the invoice against EN 16931, then hands back a download link — a PDF with the matching e-invoice XML embedded — and emails you a copy.
5. Explains anything missing in plain language — if a required detail is absent, it tells you what to add rather than failing silently.

You stay in the conversation the whole time; there's no separate app or dashboard.

Examples

Things you can say to your assistant once the skill is installed:

German B2B invoice (ZUGFeRD)

Invoice Beispiel GmbH for 12 hours of web development at €110/hour, 19% VAT. I'm Example GmbH, VAT ID DE123456789.

Returns a ZUGFeRD invoice — a PDF a human can read, with EN 16931 XML embedded for the recipient's accounting system.

German public-sector invoice (XRechnung)

Same client, but it's for the City of Munich — the Leitweg-ID is 04011000-1234512345-06.

A Leitweg-ID tells Scribo this is a B2G invoice, so it produces XRechnung, the format German public authorities require.

US invoice (plain PDF)

Bill Acme Inc. $4,000 for a brand strategy workshop.

A clean PDF invoice — no e-invoice XML, since the US has no e-invoicing mandate.

Re-download a past invoice

Send me the download link for the invoice I made for Beispiel GmbH last week.

Scribo returns a fresh download link for an invoice you've already generated.

Compliance

Scribo emits invoices conforming to EN 16931, the European e-invoicing standard, with the relevant national CIUS. Every EN 16931 output (ZUGFeRD, XRechnung) is validated against the Invopop-hosted validator at generate-time — output that fails the rule set never reaches the user. US plain PDFs carry no EN 16931 XML and are rendered directly.

Supported formats

Disclaimer: Scribo generates and validates compliant invoice documents. It is not tax or legal advice — Scribo does not determine your tax obligations, VAT treatment, or filing requirements.

FAQ

Yes — free forever. No credit card, no subscription, no paywall before your first invoice. You just need a sender email.

No signup form. On your first invoice, Scribo verifies the sender email — a 6-digit code (or one-click link) arrives at that address; one verification covers ~30 minutes of invoicing. The same email doubles as your magic-link login for re-downloads later.

Live today: Germany — ZUGFeRD (B2B) and XRechnung (B2G) — and the United States (plain PDF). Coming next: France (Factur-X), Spain (Facturae), and Belgium / NL / LU / AT (Peppol BIS 3.0).

Every EN 16931 output (ZUGFeRD, XRechnung) is validated against the EN 16931-1:2017 rule set (via the Invopop-hosted validator) before it's returned. Output that fails validation never reaches you. US plain PDFs carry no EN 16931 XML, so no schematron validation applies.

Yes. There is no US e-invoicing mandate, so Scribo produces a fully compliant plain PDF.

No. Scribo generates and validates compliant invoice documents. It does not determine your tax obligations, VAT treatment, or filing requirements.

Scribo is built to be operated by an agent. It ships as an MCP server, a CLI, and a Claude/Codex skill, plus a public HTTP API and a web app — all on the same backend. An agent can discover Scribo, create an invoice, and return the file on a user's behalf.

Causa Prima — a company building agentic AI for the CFO office. Operated by Causa Prima Germany GmbH, Munich.

Resources

• Web app — scribo.causaprima.ai
• Documentation — scribo.causaprima.ai/docs
• Compliance & trust — scribo.causaprima.ai/compliance
• Causa Prima — causaprima.ai

Other Scribo surfaces

• Skill (Claude / Codex) — scribo-skill · docs
• MCP server — scribo-mcp · docs
• CLI — scribo-cli · docs
• HTTP API — scribo-api-docs · docs
• Brand hub — scribo

License

Proprietary — UNLICENSED. © Causa Prima Germany GmbH. All rights reserved. Distributed for use against the public Scribo API; not open-source. See LICENSE.