mcp-ksef-pl 🇵🇱

English | Polski

A Python MCP server providing tools for Polish electronic invoicing compliant with KSeF (FA(2)) and Peppol BIS Billing 3.0 / EN 16931. It enables AI agents (Claude, IDEs) to generate, validate, and submit invoices to the Krajowy System e-Faktur (KSeF), as well as validate Polish tax identifiers (NIP and REGON).

Built on

This package is built on mcp-einvoicing-core, the shared base library for European e-invoicing MCP servers. It provides an OAuth2 HTTP client, token cache, data models, logging utilities, and an exception hierarchy.

mcp-einvoicing-core is installed automatically as a dependency, no additional step is required.

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🏗️ Architecture

The server acts as an intelligent communication interface between the AI agent and the KSeF platform and the Peppol network:

[ ERP System / Application ] <--> [ MCP Server ] <--> [ KSeF (MF) / Peppol Network ]
          ^                           |
          |                           v
   [ AI Agent (Claude) ] <--- (FA(2) / EN 16931)

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🛠️ Available tools

FA(3) / FA(2) invoice handling

Tool	Description
generate_fa3_invoice	Generates a KSeF-compliant FA(3) XML invoice (required for KSeF API v2 submissions)
generate_fa2_invoice	Generates a KSeF-compliant FA(2) XML invoice (legacy format, read-only use)
validate_fa3_invoice	Validates FA(3) XML: XSD validation and FA(3)-specific business rules
validate_fa2_invoice	Validates FA(2) XML: XSD validation (if the schema is available) and business rules
parse_fa2_invoice	Parses FA(2) XML into a structured dictionary

KSeF lifecycle

Tool	Description
submit_invoice_to_ksef	Submits an FA(3) invoice to the KSeF platform and returns a reference number
get_ksef_invoice_status	Retrieves the processing status of an invoice by its reference number
search_ksef_invoices	Searches invoices in KSeF by date range and direction (seller/buyer)

Identifier validation

Tool	Description
validate_polish_nip	Validates a NIP (10-digit tax identification number) using a checksum algorithm
validate_polish_regon	Validates a REGON (9- or 14-digit registry number) using a checksum algorithm

Peppol / EN 16931

Tool	Description
generate_peppol_invoice	Generates a UBL 2.1 invoice compliant with Peppol BIS Billing 3.0 / EN 16931

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🚀 Installation

Via PyPI (recommended)

pip install mcp-ksef-pl

Or without prior installation using uvx:

uvx mcp-ksef-pl

From source

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

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⚙️ Configuration (environment variables)

Variable	Default	Description
KSEF_ENVIRONMENT	test	KSeF environment: production or test
KSEF_SESSION_TOKEN	—	KSeF session token (obtained through the challenge-response flow with MF)
KSEF_NIP	—	NIP of the entity submitting invoices
KSEF_TIMEOUT	30	HTTP request timeout in seconds
KSEF_VERIFY_MF_KEY_PINNING	false	Enforce SPKI SHA-256 pinning on the MF encryption certificate. No-op until fingerprints are populated for the active environment, even when set to true

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🔐 KSeF authentication

KSeF API v2 uses a multi-step challenge/redeem flow to issue an AccessToken. This MCP server accepts an already-obtained token and cannot automate the signing step (it requires a qualified electronic signature).

Step-by-step flow

1. Account setup. Register at the KSeF portal: https://ksef.mf.gov.pl/. Select the target environment (test or production). The test environment is at https://ksef-test.mf.gov.pl/.

2. Request a challenge. Call the KSeF API to obtain a challenge XML envelope:

   curl -s https://ksef-test.mf.gov.pl/api/online/Session/AuthorisationChallenge \
     -H "Accept: application/json" \
     -d '{"contextIdentifier": {"type": "onip", "identifier": "YOUR_NIP"}}' \
     -H "Content-Type: application/json"
   

   The response contains a challenge string and a timestamp.

3. Sign the challenge. Build an <InitSessionTokenRequest> XML envelope containing the challenge, then sign it with your qualified e-signature. Accepted signing tools:

   • Qualified e-signature providers: KIR (Szafir), Certum, Sigillum
   • podpis.gov.pl (government signing portal)
   • Profil Zaufany (Trusted Profile): https://www.podatki.gov.pl/ksef/

   Example using xmlsec1 with a PKCS#12 certificate:

   # Build the challenge XML (template at specs/przyklad-wyzwania.xml)
   xmlsec1 --sign --pkcs12 your-cert.p12 --pwd "password" \
     --output signed-challenge.xml challenge-template.xml
   

4. Submit the signed challenge. POST the signed XML to obtain an AccessToken:

   curl -s https://ksef-test.mf.gov.pl/api/online/Session/AuthoriseXades \
     -H "Content-Type: application/octet-stream" \
     --data-binary @signed-challenge.xml
   

   The response contains sessionToken.token (the AccessToken) and sessionToken.context.referenceNumber.

5. Set the token. Export the token for this MCP server:

   export KSEF_SESSION_TOKEN="<the AccessToken from step 4>"
   

   The token is valid for approximately 2 hours from issuance (per MF documentation). After expiry, repeat steps 2-4.

References

• KSeF technical documentation: https://www.podatki.gov.pl/ksef/dokumentacja-techniczna-ksef/
• Authentication spec (CIRFMF): https://github.com/CIRFMF/ksef-docs/blob/main/uwierzytelnianie.md
• Interactive session spec (CIRFMF): https://github.com/CIRFMF/ksef-docs/blob/main/sesja-interaktywna.md
• FA(3) migration announcement: specs/ksef-v2-fa3-migration-announcement-20250630.pdf

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🤖 Claude Desktop integration

Add the following configuration to your claude_desktop_config.json file:

{
  "mcpServers": {
    "ksef-pl": {
      "command": "uvx",
      "args": ["mcp-ksef-pl"],
      "env": {
        "KSEF_ENVIRONMENT": "test",
        "KSEF_SESSION_TOKEN": "<your-ksef-session-token>",
        "KSEF_NIP": "<your-nip>"
      }
    }
  }
}

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⌨️ Cursor integration

Cursor supports MCP servers via stdio. Add the configuration to:

• Globally (all projects): ~/.cursor/mcp.json
• Per project (this repository only): .cursor/mcp.json

{
  "mcpServers": {
    "ksef-pl": {
      "command": "uvx",
      "args": ["mcp-ksef-pl"],
      "env": {
        "KSEF_ENVIRONMENT": "test",
        "KSEF_SESSION_TOKEN": "<your-ksef-session-token>",
        "KSEF_NIP": "<your-nip>"
      }
    }
  }
}

Reload the Cursor window (Ctrl+Shift+P → Reload Window) after saving changes.

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🪐 Kiro integration

Kiro supports MCP servers through a dedicated configuration file:

• Globally: ~/.kiro/settings/mcp.json
• Workspace: .kiro/settings/mcp.json

{
  "mcpServers": {
    "ksef-pl": {
      "command": "uvx",
      "args": ["mcp-ksef-pl"],
      "env": {
        "KSEF_ENVIRONMENT": "test",
        "KSEF_SESSION_TOKEN": "<your-ksef-session-token>",
        "KSEF_NIP": "<your-nip>"
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

Security tip: instead of entering the token directly, use the syntax "KSEF_SESSION_TOKEN": "${KSEF_SESSION_TOKEN}", as Kiro resolves shell environment variables at startup.

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📋 XSD schema

The official FA(2) and FA(3) XSD schemas ship inside the package (src/mcp_ksef_pl/schemas/) and are loaded automatically via importlib.resources — no manual download or configuration is required. validate_fa2_invoice and validate_fa3_invoice run full XSD validation out of the box for every installation.

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🧪 Tests

# Run unit tests
uv run pytest tests/ -v

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Other e-invoicing MCP servers

Country	Server
🌍 Global	mcp-einvoicing-core
🇧🇪 Belgium	mcp-einvoicing-be
🇧🇷 Brazil	mcp-nfe-br
🇫🇷 France	mcp-facture-electronique-fr
🇩🇪 Germany	mcp-einvoicing-de
🇮🇹 Italy	mcp-fattura-elettronica-it
🇵🇱 Poland	mcp-ksef-pl
🇪🇸 Spain	mcp-facturacion-electronica-es

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📄 License

This project is distributed under the Apache 2.0 license. See the LICENSE file for details.

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Project maintained by cmendezs. For questions about the KSeF or Peppol implementation, open an Issue.