io.github.matematicsolutions/nl-eli-mcp

nl-eli-mcp

Install (one command)

As a Claude plugin (Claude Code or the desktop app, needs uv); see plugin/README.md for what it sends and stores:

/plugin marketplace add matematicsolutions/nl-eli-mcp
/plugin install nl-eli-mcp@nl-eli-mcp

Published on PyPI + MCP Registry (io.github.matematicsolutions/nl-eli-mcp). Run without cloning:

uvx nl-eli-mcp

Configure your MCP client (stdio):

{ "mcpServers": { "nl-eli-mcp": { "command": "uvx", "args": ["nl-eli-mcp"] } } }

Windows 11 with Smart App Control

Smart App Control blocks unsigned executables, which covers uvx.exe, pip.exe and the nl-eli-mcp.exe launcher that pip writes at install time. The python.exe and py.exe from the python.org installer are signed by the Python Software Foundation, so running the module through the interpreter works:

python -m pip install nl-eli-mcp
python -m nl_eli_mcp

pip.exe is blocked for the same reason, so install with python -m pip, not pip install. If python is not on PATH, use the Windows launcher: py -3 -m nl_eli_mcp.

{ "mcpServers": { "nl-eli-mcp": { "command": "python", "args": ["-m", "nl_eli_mcp"] } } }

Do not turn Smart App Control off to work around this - it cannot be re-enabled without reinstalling Windows.

Building from source: see Install.

An MCP server for the Dutch consolidated legislation BWB (Basiswettenbestand), served by KOOP over the official SRU API (zoekservice.overheid.nl, keyless). It gives an AI agent the version of an act in force on a given date, with a verifiable citation: a persistent identifier, a human-readable citation, and a link to the official source.

Part of the eu-legal-mcp line by MateMatic — one connector per EU member state, the same citation contract everywhere.

On ELI. The Netherlands does not publish native ELI (/eli/) URIs on consolidated BWB. To keep the line's contract honest, eli_uri carries the official persistent identifier instead — the wetten.overheid.nl/id toestand URI (e.g. http://wetten.overheid.nl/id/BWBR0005537/2026-06-04/0). The connector never fabricates an /eli/ URI and says so in its tool instructions. See DISCOVERY.md.

Tools

Legislation comes from the BWB (KOOP SRU); case law comes from Rechtspraak Open Data (data.rechtspraak.nl), keyed by native ECLI. Every response carries the citation contract:

• eli_uri — the official persistent identifier (toestand URI; see the ELI note above).
• human_readable_citation — the official short title (citeertitel), e.g. Algemene wet bestuursrecht.
• source_url — the browsable wetten.overheid.nl page for that version.

Versions and dates

Each act has many time-stamped versions. The tools default to the version in force today; pass on_date (YYYY-MM-DD) to pin a historical or future version. An act with no version valid on that date returns not_found — retry with another on_date.

Install

pip install -e ".[dev]"

Register it with your MCP client (see .mcp.json.example):

{
  "mcpServers": {
    "nl-eli-mcp": {
      "command": "nl-eli-mcp",
      "env": {
        "NL_ELI_BASE_URL": "https://zoekservice.overheid.nl/sru/Search",
        "NL_ELI_CACHE_DIR": "~/.matematic/cache/nl-eli",
        "NL_ELI_AUDIT_DIR": "~/.matematic/audit"
      }
    }
  }
}

Design

• Public data only. Read-only against the keyless KOOP SRU API, the official repository host and Rechtspraak Open Data; nothing is sent beyond the query / identifier and the date.
• Audit log. Every call appends one JSON line to ~/.matematic/audit/nl-eli-mcp.jsonl (record-keeping).
• Network. Besides the sources above, once on first use the server fetches a small configuration file (nl-runtime.json.gz, updated source addresses) from this repository's GitHub Releases. That request carries no query content; GitHub's download counter for the file is the only usage signal we see. NL_ELI_RUNTIME_URL="" turns it off; the Claude plugin ships with it off. No LLM provider, no other telemetry; own backoff + on-disk cache.
• No fabrication. Identifiers and titles are parsed from the source record. If KOOP's schema changes, the connector fails loudly rather than returning stale or invented data.

See CONSTITUTION.md (the 4 principles) and DISCOVERY.md (how the source was mapped).

Tests

pytest tests/test_instructions_drift.py tests/test_parse.py   # offline
pytest tests/test_smoke.py                                     # live KOOP API

Licence

Apache-2.0. The Dutch legislation served is official public data of the Kingdom of the Netherlands; this connector adds no rights over it.