nl-eli-mcp

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

Tool	What it does
nl_search(query, on_date=today)	Find acts by words in the title that are in force on a date. Returns distinct acts, each with the citation contract.
nl_get_act(bwb_id, on_date=today)	Metadata for one act (e.g. BWBR0005537) — identifier, title, authority, version date.
nl_get_text(bwb_id, on_date=today)	The full consolidated XML (BWB toestand) of one act.
nl_case_search(date_from, date_to, ...)	List court decisions (Rechtspraak Open Data) by date range / court / subject. No free-text; each hit carries a native ecli.
nl_get_decision(ecli)	A court decision by its ECLI (e.g. ECLI:NL:HR:2020:1) — court, dates, zaaknummer and full text.

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 and the official repository host; 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 (AI Act art. 12 record-keeping).
• Vendor-neutral. No LLM provider, no 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.