io.github.cmendezs/mcp-ksef-pl

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).

Introduction

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.

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

Configuration (environment variables)

The EUSR/TSR reporting and MLS tools additionally require the [xslt2] extra (pip install "mcp-ksef-pl[xslt2]") for Schematron validation.

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>"
      }
    }
  }
}

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.

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.

Available tools

FA(3) / FA(2) invoice handling

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.

KSeF lifecycle

Identifier validation

Peppol / EN 16931

Peppol network tools

Peppol participant lookup, service-endpoint lookup, a DNS-only diagnostic, AS4 send, Peppol Directory search, and the OpenPeppol eDEC codelist tools are provided by the shared core Peppol tool plugin (mcp_einvoicing_core.peppol.tools.register_peppol_tools), mounted in server.py with a Poland-specific identifier adapter: a bare NIP (e.g. 1234563218) is normalized to the 9945:<digits> Peppol scheme (PL:VAT, per the OpenPeppol eDEC Participant Identifier Schemes code list); an already scheme-qualified identifier (e.g. 9945:1234563218) passes through unchanged. Use these tools to check PEF (Poland's Peppol Access Point for public-procurement B2G invoicing) registration status ahead of generate_peppol_invoice.

peppol_send signs outbound messages with a real wsse:Security signature as of mcp-einvoicing-core v1.20.0 (previously computed and discarded — see CHANGELOG.md v0.8.0).

See the mcp-einvoicing-core README for full parameter documentation on these tools.

Peppol reporting and status tools

Added in v0.8.0 via three opt-in core plugins, mounted unconditionally in server.py. Each raises a clear error at call time (not at registration) if its extra or data directory is missing.

See the mcp-einvoicing-core README for full parameter documentation on these tools.

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/auth/challenge \
      -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 receive an authOperation reference:

    curl -s https://ksef-test.mf.gov.pl/auth/xades-signature \
      -H "Content-Type: application/octet-stream" \
      --data-binary @signed-challenge.xml

5. Redeem the AccessToken. Exchange the authenticated operation for an AccessToken:

    curl -s https://ksef-test.mf.gov.pl/auth/token/redeem \
      -H "Content-Type: application/json" \
      -H "Authorization: Bearer <referenceNumber-or-authOperation-token-from-step-4>"

   The response contains accessToken.token and accessToken.context.referenceNumber.

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

    export KSEF_SESSION_TOKEN="<the AccessToken from step 5>"

   The token is valid for approximately 2 hours from issuance (per MF documentation). After expiry, repeat steps 2-5.

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

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)

Vendor neutrality

This server implements the standard itself: it builds, validates, and signs the document locally. It is not a client for a commercial invoicing platform, and your signing keys and credentials never leave your own infrastructure.

Invoices go directly to KSeF with your own authentication token; no intermediary is involved.

Tests

# Run unit tests
uv run pytest tests/ -v

Contributing

Contributions are welcome — see CONTRIBUTING.md for guidelines.

Other e-invoicing MCP servers

License

This project is distributed under the Apache 2.0 license. See the LICENSE file for details. For the full version history, see CHANGELOG.md.