mcp-ksef-pl 🇵🇱

English | Polski

<!-- mcp-name: io.github.cmendezs/mcp-ksef-pl -->

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).

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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)

| 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 | | EINVOICING_PEPPOL_CODELIST_DIR | — | Local directory containing your own copy of the OpenPeppol eDEC Code Lists, required by the Peppol codelist tools (not bundled with this package; see mcp-einvoicing-core README) | | EINVOICING_EN16931_CODELIST_DIR | — | Local directory containing your own copy of the CEF "Digital Building Blocks" EN 16931 semantic code lists, required by the EN 16931 codelist tools (not bundled; see mcp-einvoicing-core README) |

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

| 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 |

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

| 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 | | validate_peppol_invoice | Validates a UBL 2.1 Peppol invoice against the CEN EN 16931 base Schematron rules (en16931-base-only scope — does not check the Peppol-specific overlay) |

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).

| Tool | Description | |------|-------------| | peppol_lookup_participant | Check whether a business is registered on the Peppol network; returns registration status and supported document types | | peppol_get_service_endpoint | Fetch the AS4 endpoint for a participant's document type | | resolve_peppol_dns | DNS-only (SML) diagnostic, independent of SMP reachability | | peppol_send | Transmit a UBL/CII invoice via AS4 | | peppol_directory_search | Search the public Peppol Directory by participant, name, country, or document type | | list_participant_id_schemes, list_document_type_ids, list_process_ids, list_spis_use_case_ids | OpenPeppol eDEC codelist lookups (require EINVOICING_PEPPOL_CODELIST_DIR) | | check_document_type_id_in_codelist, check_process_id_in_codelist, check_participant_id_scheme_in_codelist, get_peppol_codelist_version | OpenPeppol eDEC codelist checks and version reporting |

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.

| Tool | Plugin | Description | |------|--------|-------------| | validate_eusr_report | register_peppol_reporting_tools | Validate an End User Statistics Report (XSD, then Schematron). Requires the [xslt2] extra. | | validate_tsr_report | register_peppol_reporting_tools | Validate a Transaction Statistics Report (XSD, then Schematron). Requires the [xslt2] extra. | | validate_mls_message | register_peppol_mls_tools | Validate a Message Level Status document (UBL ApplicationResponse-2 subset). Requires the [xslt2] extra. | | build_mls_message | register_peppol_mls_tools | Build a document-level MLS response. Requires the [xslt2] extra. | | 13 list_*/check_* pairs, get_en16931_codelist_version | register_en16931_codelist_tools | EN 16931 semantic code list lookups/checks (units, VAT categories, etc.). Require EINVOICING_EN16931_CODELIST_DIR. |

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 techni