MCP E-Invoicing Core

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 shared Pydantic models, EN 16931 invoice tree, UBL/CII wire format serializers, an OAuth2 HTTP client, Peppol SMP lookup, digital signature primitives, and a compliance audit framework so country-specific packages share a common foundation without duplicating code.

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What this package provides

Module	Contents
models	InvoiceDocument, InvoiceParty, InvoiceLineItem, PartyAddress, VATSummary, PaymentTerms, DocumentValidationResult, TaxIdentifier (per-country tax ID validators: IT, FR, DE, BE, ES, PL, BR, AE, SG, MX, IN), TaxIdValidationResult
en16931	EN16931Invoice, EN16931Party, EN16931LineItem, EN16931Address, EN16931Tax, EN16931AllowanceCharge, EN16931PaymentMeans
credit_note	EN16931CreditNote (type codes 381/383/384/385), BillingReference
ubl_documents	BaseUBLDocument — shared envelope for non-invoice UBL/Peppol document families (Peppol Ordering, jurisdiction extensions); explicitly outside the InvoiceDocument/EN16931Invoice tree
wire_formats	EN16931UBLSerializer, EN16931UBLParser, EN16931CIISerializer, EN16931CIIParser, UBL_NSMAP, CII_NSMAP
convert	Syntax (UBL, CII), convert_wire_format (auto-detect source, serialize to target)
base_server	EInvoicingMCPServer, BaseDocumentGenerator, BaseDocumentValidator, BaseDocumentParser, BaseLifecycleManager, BasePartyValidator, BaseScopeInfo, SubmissionMetadata, SearchCriteria, SubmitResult, assert_not_read_only, scrub
http_client	BaseEInvoicingClient (OAuth2, mTLS, bearer, API key, JWS, none), OAuthConfig, OAuthValues, JWSConfig, APIKeyConfig, TokenCache, AuthMode
peppol	PeppolSMPClient, PeppolParticipantId, PeppolServiceInfo, PeppolLookupResult, PeppolEnvironment, PEPPOL_BIS_BILLING_30, resolve_naptr (standalone U-NAPTR/SML DNS diagnostic)
peppol.tools	register_peppol_tools (mountable FastMCP plugin: participant lookup, service endpoint, DNS diagnostic, AS4 send, Directory search, plus 8 eDEC code list tools), default_id_adapter, IdentifierAdapter (national identifier adapter contract)
peppol.codelists	CodeList, CodelistNotConfiguredError, load_codelist and the eDEC lookup functions (document types, processes, participant ID schemes, transport profiles, SPIS use cases). Requires EINVOICING_PEPPOL_CODELIST_DIR, see Configuration below
genericode	parse_genericode, CodeList, CodelistNotConfiguredError — shared OASIS Genericode 1.0 parser (used by peppol.codelists and en16931_codelists)
en16931_codelists	en16931_codelist_tools.register_en16931_codelist_tools (mountable FastMCP plugin: country, currency, ICD, UNCL1001/1153/4461/5305, allowance/item/charge reason, MIME, EAS, VATEX lookup). Requires EINVOICING_EN16931_CODELIST_DIR, see Configuration below
peppol.directory	PeppolDirectoryClient (public Peppol Directory REST search, no auth), PeppolDirectorySearchResult, PeppolBusinessCard, PeppolBusinessEntity
peppol.transport	AS4MessageEnvelope, AS4TransportClient, AS4ReceiptHandler, PeppolTransmitter, AS4Receipt, AS4Credentials (Peppol AS4 outbound transmission, now with real WS-Security message signing); AS4InboundHandler, AS4InboundMessage, AS4InboundError, StandardBusinessDocumentHeader (AS4 inbound receiver, C3 role); sign_as4_message, verify_as4_signature (WS-Security primitives)
peppol.trust	PeppolTrustStore, validate_certificate_chain, check_revocation, verify_smp_signature — OpenPeppol PKI chain/revocation/signature validation. Requires EINVOICING_PEPPOL_PKI_DIR (root certs not yet published by OpenPeppol as of this release — logic-only until supplied)
peppol.reporting	parse_eusr, parse_tsr, validate_eusr, validate_tsr — Peppol EUSR/TSR service-provider statistics report models and validation (bundled XSD + Schematron, optional [xslt2] extra)
peppol.mls	parse_mls, validate_mls, build_mls — Peppol Message Level Status (MLS) model and validation (bundled Schematron, optional [xslt2] extra)
schematron	SchematronValidator (XSLT 1.0), SaxonSchematronValidator (XSLT 2.0/3.0, optional [xslt2] extra), load_schematron_validator (auto-dispatch factory), get_xslt_version, BaseStructuredValidator, BaseXSDValidator, XSDValidator (generic concrete XSD validator), BaseJSONValidator, ValidationMessage, ValidationResult
schematron_artifacts	en16931_base_schematron_validator (bundled, compiled CEN EN16931 base Schematron — BR-* rules only, no Peppol overlay; optional [xslt2] extra)
digital_signature	BaseDocumentSigner, XAdESEPESSigner, XAdESSignerConfig, XMLDSigSigner, XMLDSigSignerConfig, CAdESSigner, CAdESSignerConfig, SelloDigitalSigner, SelloDigitalSignerConfig, load_certificate_der
endpoints	BaseEnvironmentEndpoints, EndpointSet, EndpointEnvironment (sandbox/production URL routing)
routing	RoutingIdentifier (static validators: validate_de_leitweg), RoutingIdValidationResult
profile_registry	ProfileEntry, ProfileRegistry, profile_registry, set_profile_registry
pdf	PDFEmbedder (PDF/A-3 XML embedding); extract(filename=None) tries canonical Factur-X/XRechnung/ZUGFeRD filenames in turn, identify() reads XMP to detect a hybrid PDF and its conformance level
pdf_tools	register_pdf_tools (mountable FastMCP plugin: identify_and_extract_pdf), identify_and_extract_pdf
qr	generate_qr_png_base64
xml_utils	format_amount, format_quantity, xml_element, xml_optional, validate_date_iso, validate_iban, resolve_xml_input, mark_untrusted, mark_untrusted_fields, filter_empty_values, format_error
download_rules	DownloadSpec, download_artefacts
testing	InvoiceFixtureFactory (shared pytest fixtures)
audit_log	AuditLog, AuditAction, get_audit_log
confirmation	ConfirmationGate, ConfirmationStore (human-in-the-loop gate)
exceptions	EInvoicingError, ValidationError, PartyValidationError, XSDValidationError, SchematronValidationError, DocumentGenerationError, AuthenticationError, PlatformError
logging_utils	setup_logging, get_logger
audit	Compliance audit framework: AuditReport, CheckResult, CheckFinding, severity constants, make_report, render_summary_table, parse_audit_args, run_check_core_coverage, run_check_version_compatibility, run_check_known_shared_helpers, run_check_resource_paths, TaxRate, load_rates (optional [audit] extra)

Country packages

Country	Package	Standard	Scope	Coverage status
🇧🇪 Belgium	mcp-einvoicing-be	Peppol BIS 3.0 / PINT-BE	B2B, 1 January 2026	Live; Peppol-specific overlay rules not checked (EN 16931 base only)
🇧🇷 Brazil	mcp-nfe-br	NF-e / NFC-e (modelo 55/65, schema 4.00) / NFS-e Nacional	B2B (NF-e) + B2C (NFC-e), both mandatory since 2008	Live; IBS/CBS tax reform rollout ongoing through 2033
🇫🇷 France	mcp-facture-electronique-fr	NF XP Z12-012 / NF XP Z12-013 / Factur-X / UBL 2.1 / CII	B2B, phased rollout from 1 September 2026	Live
🇩🇪 Germany	mcp-einvoicing-de	ZUGFeRD 2.x / XRechnung 3.x	B2B, phased 2025 to 2028	Live
🇮🇳 India	mcp-einvoicing-in	GST e-invoicing / FORM GST INV-01 schema v1.1 / IRP-IRN (INV + CRN + DBN)	B2B + B2G, mandatory under CGST Rule 48(4) for taxpayers with AATO above ₹5 crore, since 1 August 2023	Pre-release (v0.1.0, unpublished); Phase A only (build + offline validation + QR rendering) — live IRP submission pending the NIC API spec
🇮🇹 Italy	mcp-fattura-elettronica-it	FatturaPA / SDI	B2G + B2B + B2C, mandatory since 2019 (B2G since 2014)	Live
🇲🇽 Mexico	mcp-cfdi-mx	CFDI 4.0 / Complemento de Pagos 2.0	B2B + B2G, mandatory nationwide	Live; PAC submission transport pending
🇵🇱 Poland	mcp-ksef-pl	KSeF FA(3) / FA(2) / Peppol BIS 3.0	B2B, phased February 2026 to January 2027	Live; batch session flow not implemented
🇸🇬 Singapore	mcp-invoicenow-sg	PINT-SG v1.4.1 / SG Peppol BIS Billing 3.0	B2B, mandatory for GST-registered businesses from April 2026	Live; validation scope limited to IRAS C5 acceptance checks, PINT-SG jurisdiction Schematron and EN 16931 base validation not yet wired
🇪🇸 Spain	mcp-facturacion-electronica-es	Factura-e / VeriFactu / SII / FACe	Pending Orden Ministerial, targeted 2026-10-01	Live for VeriFactu/SII; B2B format wiring blocked on pending Orden Ministerial
🇦🇪 United Arab Emirates	mcp-einvoicing-ae	PINT AE (billing + self-billing) / Peppol AE TDD	B2B + B2G, voluntary pilot from July 2026, mandatory for large taxpayers from January 2027	Live; validates CEN EN16931 base Schematron only, PINT AE jurisdiction overlay and TDD validation not yet available

Installation

pip install mcp-einvoicing-core

For the compliance audit framework (used by country package CI):

pip install mcp-einvoicing-core[audit]

For XSLT 2.0/3.0 Schematron validation (SaxonSchematronValidator — needed for Schematron rule sets using XPath 2.0+ constructs, e.g. FNFE-MPE Factur-X 1.08 / ZUGFeRD):

pip install mcp-einvoicing-core[xslt2]

Configuration

Variable	Used by	Purpose
EINVOICING_PEPPOL_CODELIST_DIR	peppol.codelists (and the peppol.tools codelist tools)	Local directory containing your own copy of the OpenPeppol eDEC Code Lists. Not bundled with this package: the eDEC Code Lists carry no confirmed redistribution grant from OpenPeppol, so core ships only the parser and lookup tools, never the data itself. Download the "as GeneriCode" export for each artifact (Document Types, Participant Identifier Schemes, Processes, Transport Profiles, SPIS Use Case) from docs.peppol.eu/edelivery/codelists and point this variable at the directory containing them. Filenames are matched by prefix, so a version bump (e.g. v9.7 to v9.8) needs no code change. Without this set, the codelist tools return a configured: false result with setup instructions rather than raising.
EINVOICING_EN16931_CODELIST_DIR	en16931_codelists (and its FastMCP tools)	Local directory containing your own copy of the CEF EN 16931 semantic code lists (country, currency, ICD, UNCL1001/1153/4461/5305, allowance/item/charge reason, MIME, EAS, VATEX). Not bundled, same posture as the eDEC lists above — download the "as GeneriCode" export bundle from the CEF EN 16931 code lists page. Filenames match exactly (Country.gc, not a version-prefixed name). Without this set, tools return configured: false.
EINVOICING_PEPPOL_PKI_DIR	peppol.trust	Local directory with test/ and prod/ subdirectories of PEM-encoded OpenPeppol PKI root/intermediate CA certificates, for AS4 message signature and SMP response signature chain validation. Not yet published by OpenPeppol as bundled data anywhere — trust functions report trust_anchors_configured: false until this is set.
EINVOICING_SMP_ALLOWLIST	peppol (PeppolSMPClient, resolve_naptr)	Comma-separated hostname suffixes to extend the built-in Peppol Access Point allowlist used when validating a resolved SMP hostname.
EINVOICING_CERT_PINS	http_client (BaseEInvoicingClient) and peppol.transport.client (AS4TransportClient)	Comma-separated host:sha256hex pairs enabling SHA-256 certificate pinning on outbound HTTP requests. Without this set, pinning is not enforced.

Architecture

Country packages subclass the core abstractions and register their tools on a shared or standalone MCP server:

mcp-einvoicing-core
  ├── EN16931Invoice / InvoiceDocument  ← canonical invoice models
  ├── EN16931CreditNote                 ← credit note (type codes 381/383/384/385)
  ├── EN16931UBL/CII Serializer/Parser  ← wire format round-trip
  ├── convert_wire_format               ← CII ↔ UBL conversion
  ├── BaseDocumentGenerator/Validator/Parser/LifecycleManager
  ├── BaseEInvoicingClient              ← async HTTP (OAuth2/mTLS/bearer/API key/JWS)
  ├── PeppolSMPClient                   ← participant lookup via SMP/SML
  ├── PeppolTransmitter                 ← AS4 outbound transmission
  ├── BaseDocumentSigner                ← XAdES-EPES / XMLDSig
  ├── BaseEnvironmentEndpoints          ← sandbox/production URL routing
  ├── RoutingIdentifier                 ← country-specific routing ID validation
  ├── EInvoicingMCPServer               ← plugin registry wrapping FastMCP
  └── Audit framework                   ← per-package compliance checks

Vendor neutrality

Every server in this family implements the standard itself. It builds, validates and signs the document locally, and the signing keys stay in your infrastructure. None of these packages is a client for a commercial invoicing platform, and no vendor account is needed to run one.

What differs between countries is the last mile: who, if anyone, must stand between you and the tax authority. mcp-einvoicing-core supports all three arrangements, and each country package implements exactly the one its jurisdiction uses:

• Direct to the authority. No intermediary is legally required; the package talks to the government endpoint with your own accreditation. (Italy, Poland, Brazil, Spain)
• Substitutable intermediary. An intermediary is required, but its API is standardized, so changing provider is a configuration change, not a code change. (France's PDP under XP Z12-013; Peppol access points for Belgium, Singapore, the UAE)
• Adapter-per-vendor intermediary. An intermediary is required and each vendor's API differs. The document and the keys still stay yours; only the transport adapter is vendor-specific. (Mexico's PAC, India's GSP)

In all three, the compliance logic and the private keys stay with you.

Plugin registration pattern

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

# Standalone
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()

Core also ships its own mountable Peppol tool plugin so country packages stop reimplementing SMP lookup and AS4 send. Supply a national identifier adapter (a small function that normalizes a bare national number, e.g. a VAT number, into a Peppol "<scheme>:<value>" participant ID):

from mcp_einvoicing_core.peppol.tools import register_peppol_tools

def be_id_adapter(identifier: str) -> str:
    if ":" in identifier:
        return identifier
    return f"0208:{normalize_vat_be(identifier)[2:]}"  # KBO/BCE scheme

server.register_plugin(
    lambda m: register_peppol_tools(m, id_adapter=be_id_adapter), "peppol"
)

This registers peppol_lookup_participant, peppol_get_service_endpoint, resolve_peppol_dns, peppol_send, peppol_directory_search, and 8 OpenPeppol eDEC code list tools (see Configuration above for EINVOICING_PEPPOL_CODELIST_DIR, required for the code list tools). Separate mountable plugins cover the EN 16931 semantic code lists (en16931_codelist_tools.register_en16931_codelist_tools), Peppol reporting (peppol.reporting_tools.register_peppol_reporting_tools), and MLS (peppol.mls_tools.register_peppol_mls_tools).

Claude Desktop / Cursor / Kiro compatibility

Existing configurations for country packages require no changes: tool names, signatures, environment variables, and entry points (server:main) are fully preserved.

License

Apache 2.0 -- see LICENSE.