Einvoicing Core MCP Server

mcp-einvoicing-core

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Topics: mcp mcp-server e-invoicing electronic-invoicing python fastmcp peppol en16931 ubl fatturapa xp-z12-013 nfe xml base-library

Base package for electronic invoicing MCP servers.

Provides abstract base classes, shared Pydantic models, XML utilities, and an HTTP client so country-specific packages (mcp-facture-electronique-fr, mcp-fattura-elettronica-it, mcp-nfe-br, …) share a common foundation without duplicating code.

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What this package provides

Installation

pip install mcp-einvoicing-core

This package has no country-specific dependencies. lxml (needed for XSD validation in IT and future countries) is declared by each country package individually.

Architecture

mcp-einvoicing-core           ← this package
  ├── BaseDocumentGenerator   ← abstract: generate(InvoiceDocument) → str
  ├── BaseDocumentValidator   ← abstract: validate(xml) → DocumentValidationResult
  ├── BaseDocumentParser      ← abstract: parse(xml) → dict
  ├── BaseLifecycleManager    ← abstract: submit/search/get_status (async HTTP)
  ├── BasePartyValidator      ← abstract: validate_seller/buyer/tax_id
  ├── BaseEInvoicingClient    ← concrete: async HTTP + OAuth2/no-auth/token
  ├── InvoiceDocument (Pydantic)  ← shared data model
  └── EInvoicingMCPServer     ← plugin registry wrapping FastMCP

mcp-facture-electronique-fr   ← country adapter (FR)
  ├── PAConfig(OAuthConfig)
  ├── FlowClient(BaseEInvoicingClient)      ← OAuth2, XP Z12-013 Annex A
  ├── DirectoryClient(BaseEInvoicingClient) ← OAuth2, XP Z12-013 Annex B
  └── FrLifecycleManager(BaseLifecycleManager)

mcp-fattura-elettronica-it    ← country adapter (IT)
  ├── ItalyPartyValidator(BasePartyValidator)   ← Partita IVA modulo-10
  ├── FatturaGenerator(BaseDocumentGenerator)   ← FatturaPA XML v1.6.1
  ├── FatturaValidator(BaseDocumentValidator)   ← lxml XSD v1.6.1
  └── FatturaParser(BaseDocumentParser)         ← lxml xpath

Plugin registration pattern

Country packages register their tools on a shared or standalone FastMCP instance:

# Standalone (existing server.py — no changes required)
from fastmcp import FastMCP
mcp = FastMCP(name="mcp-fattura-elettronica-it", instructions="…")
register_header_tools(mcp)
register_body_tools(mcp)
register_global_tools(mcp)

# Multi-country (optional EInvoicingMCPServer)
from mcp_einvoicing_core import EInvoicingMCPServer
server = EInvoicingMCPServer(name="mcp-einvoicing-eu", instructions="…")
server.register_plugin(register_header_tools, "it-header")
server.register_plugin(register_flow_tools, "fr-flow")
server.run()

Claude Desktop / Cursor / Kiro compatibility

Existing configurations for mcp-facture-electronique-fr and mcp-fattura-elettronica-it require no changes: tool names, signatures, environment variables, and entry points (server:main) are fully preserved.

Roadmap compatibility

Open backlog and sprint planning per country is in context-library/roadmap-2026.md. The table below reflects the canonical EN 16931 vs non-EN 16931 invoice pathway split (see CLAUDE.md).

Countries on the planning radar (not yet scaffolded — see roadmap-2026.md "New country packages" section): IN, MX, RO, CO, CL, PE, VN, EG, HU, GR, KR, ID, EC, UY (Category 1 — fully live clearance); SG, MY, SA, NG, IL, PY, PH (Category 2 — rolling out in 2026); UAE, OM, SK, PT, DK, ZA (Category 3 — transition or late 2026/2027). Voluntary EU/APAC/NA jurisdictions are Category 4.

Architectural notes

Transport interface

As the adapter count grows, a TransportInterface abstraction in core will prevent duplication across countries that share the same transport layer. Current adapter coverage:

A dedicated TransportInterface is tracked as architectural work; today each country adapter extends BaseEInvoicingClient directly with the auth mode it needs (AuthMode.OAUTH2_CLIENT_CREDENTIALS, AuthMode.MTLS, AuthMode.BEARER_TOKEN, AuthMode.NONE).

EN 16931 wire formats

Core ships EN16931UBLSerializer/EN16931UBLParser and EN16931CIISerializer/EN16931CIIParser (since v1.3.0) so EU country adapters do not reimplement UBL 2.1 or CII D16B serialisation. New EU country packages should extend these rather than write a parallel XML stack.

ViDA / DRR (2030)

By July 2030, all national systems must align with the EU Digital Reporting Requirements (DRR) for cross-border transactions. Using EN 16931 as the canonical EU invoice root (EN16931Invoice) already future-proofs the invoice-envelope side: country adapters translate EN16931Invoice to the local wire format, not the other way around. The DRR submission lifecycle itself (real-time structured transaction data submission to a central EU register, transaction ID issuance, cross-border 4-corner reconciliation) is not modelled in core today and is tracked as a separate workstream in roadmap-2026.md; do not equate "supports EN 16931 / Peppol" with "supports ViDA DRR".

License

Apache 2.0 — see LICENSE.