Nfe Br MCP Server

mcp-nfe-br 🇧🇷

English | Portugues (Brasil)

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Introduction

mcp-nfe-br is an MCP (Model Context Protocol) server providing tools for issuing and validating Brazilian electronic fiscal documents: NF-e (modelo 55) and NFC-e (modelo 65), per SEFAZ XML schema version 4.00. This server is part of the mcp-einvoicing-* / mcp-*-* family, built on mcp-einvoicing-core, which provides the base data model, HTTP/OAuth2 utilities, and shared MCP server infrastructure.

Current status (v0.2.0): Phase 1 of the roadmap, covering CPF/CNPJ tax-ID validation, unsigned NF-e/NFC-e XML generation, and XSD validation against the official PL_010d schema (unsigned variant). ICP-Brasil digital signing and SEFAZ webservice submission are planned for future releases. Generated documents are unsigned and are not transmitted to SEFAZ by this server. NFS-e (service invoices) and CT-e (transport documents) are later phases, out of scope for this version.

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Installation

Requirements

• Python ≥ 3.11
• mcp-einvoicing-core (installed automatically as a dependency)

Using uv (recommended)

uv add mcp-nfe-br

Using pip

pip install mcp-nfe-br

From source

git clone https://github.com/cmendezs/mcp-nfe-br.git
cd mcp-nfe-br
uv sync --all-extras

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Configuration

Add the server to your MCP client configuration. For Claude Desktop, edit claude_desktop_config.json:

{
  "mcpServers": {
    "nfe-br": {
      "command": "uvx",
      "args": ["mcp-nfe-br"]
    }
  }
}

For a local development installation:

{
  "mcpServers": {
    "nfe-br": {
      "command": "uv",
      "args": ["run", "mcp-nfe-br"],
      "cwd": "/path/to/mcp-nfe-br"
    }
  }
}

Environment variables

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Available tools

br__validate_cpf

Validates a CPF (Cadastro de Pessoas Físicas), the individual taxpayer identification number, using the Receita Federal modulo 11 algorithm.

Returns a TaxIdValidationResult with valid=True and the cleaned value (11 digits) on success, or valid=False with an error message in Portuguese.

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br__validate_cnpj

Validates a CNPJ (Cadastro Nacional da Pessoa Jurídica), the business taxpayer identification number. Accepts both the traditional numeric format (14 digits) and the alphanumeric format introduced by NT 2026.004 (PL_010d), effective in homologation from 2026-06-01 and in production from 2026-07-01.

Returns a TaxIdValidationResult with valid=True and the cleaned value (14 characters) on success, or valid=False with an error message in Portuguese.

⚠️ [Unverified]: the check-digit algorithm for the alphanumeric CNPJ format was implemented based on secondary sources, as the primary source ("NT Conjunta DFe 2025.001") is not yet available locally. See context-library/countries/br.md for details.

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br__generate_nfe

Generates an unsigned NF-e/NFC-e 4.00 document (<NFe><infNFe>…</infNFe></NFe>) from a BRInvoice object.

Returns {"xml": ..., "chave_acesso": ..., "warnings": [...]}. The warnings in Portuguese remind that the document is not signed (ICP-Brasil) and was not transmitted to SEFAZ. Both steps are the responsibility of a separate process.

Phase 1 coverage for per-item tax groups:

[NEED: IBS/CBS/Imposto Seletivo — Grupo UB/W03 (NT 2025.002-RTC) not yet modeled, see context-library/countries/br.md "Known gaps"].

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br__validate_nfe_xml

Validates an NF-e/NFC-e 4.00 XML document against the official PL_010d XSD (local "unsigned" variant, see note below).

* Exactly one of xml_content/xml_base64 must be provided.

Returns {"valid": bool, "errors": [...], "metadata": {"schema_version": ...}}.

[Inference]: the official XSD (nfe_v4.00.xsd/leiauteNFe_v4.00.xsd, PL_010d) requires <ds:Signature> as a mandatory child of <NFe>. Since Phase 1 generates unsigned documents, this tool validates against a local derived copy (nfe_v4.00_unsigned.xsd) where <ds:Signature> has been made optional (minOccurs="0"). Validation of signed documents (future phase) should use the official XSD without modifications.

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br__build_access_key

Builds an access key (chNFe, 44 characters) with a modulo 11 check digit, from the components cUF, dhEmi, issuer CNPJ, model, series, and document number.

Returns {"chave_acesso": ..., "cnf": ...}.

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Architecture

mcp-nfe-br/
├── src/
│   └── mcp_nfe_br/
│       ├── __init__.py
│       ├── server.py              # MCP entry point and tool registration
│       ├── models/
│       │   ├── __init__.py
│       │   └── invoice.py         # BRInvoice, BRInvoiceLine, NFeModelo, TipoOperacao
│       ├── standards/
│       │   ├── __init__.py
│       │   └── nfe_generator.py   # NFeGenerator — generates unsigned NF-e/NFC-e 4.00
│       ├── validators/
│       │   ├── __init__.py
│       │   └── nfe_xsd.py         # NFeXSDValidator — validates against PL_010d XSD (unsigned variant)
│       ├── schemas/nfe/           # Bundled XSDs (official + "_unsigned" variants)
│       ├── tools/
│       │   ├── __init__.py
│       │   ├── validation.py      # br__validate_cpf, br__validate_cnpj
│       │   └── generation.py      # br__generate_nfe, br__validate_nfe_xml, br__build_access_key
│       └── utils/
│           ├── __init__.py
│           ├── document_ids.py    # validate_cpf, validate_cnpj
│           └── access_key.py      # build_access_key, access_key_check_digit
├── tests/
│   ├── conftest.py
│   ├── fixtures/
│   ├── test_tools/
│   │   ├── test_validation.py
│   │   └── test_generation.py
│   ├── test_standards/
│   │   └── test_nfe_generator.py
│   ├── test_validators/
│   │   └── test_nfe_xsd.py
│   └── test_utils/
│       └── test_access_key.py
├── specs/nfe/                     # Normative material (XSDs, MOC, Technical Notes, not published)
├── audit/
│   ├── audit_vs_core.py
│   └── report.json
├── .github/workflows/publish.yml
├── pyproject.toml
├── RELEASE.md
└── LICENSE

Relationship with mcp-einvoicing-core

mcp-einvoicing-core provides:

• Base Pydantic models for invoices, parties, line items, and validation results (InvoiceDocument, InvoiceLineItem, TaxIdValidationResult)
• Shared MCP server infrastructure (EInvoicingMCPServer)
• HTTP/OAuth2 client, token cache, structured logging, exception hierarchy

mcp-nfe-br adds Brazil-specific logic:

• BRInvoice (extends InvoiceDocument, as NF-e/NFC-e has no EN 16931 lineage)
• Group I fields (NCM, CFOP, ICMS/IPI/PIS/COFINS) in BRInvoiceLine
• CPF/CNPJ validation (including the alphanumeric CNPJ from NT 2026.004)

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Contributing

Contributions are welcome. Please open an issue to discuss significant changes before submitting a pull request.

git clone https://github.com/cmendezs/mcp-nfe-br.git
cd mcp-nfe-br
uv sync --all-extras
uv run pytest
uv run ruff check src/mcp_nfe_br tests audit
uv run mypy src/mcp_nfe_br

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Other e-invoicing MCP servers

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License

This project is licensed under Apache 2.0. See LICENSE for details.

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Changelog

See RELEASE.md for the full version history.