finlex-mcp

An MCP server that gives AI assistants direct, citable access to Finnish legislation.

Ask Claude "Mitä kuluttajansuojalaki sanoo etämyynnin peruuttamisesta?" and instead of answering from memory (and possibly inventing a section number), it calls this server and answers with the actual, current text of KSL 6 luku 14 § — with the formal citation, the Finlex consolidation date, and a link to verify.

This is a retrieval tool, not legal advice. It returns statute text with citations; it never interprets law. Always verify against finlex.fi.

Demo

"Mitä kuluttajansuojalaki sanoo etämyynnin peruuttamisesta?" → Claude calls search_statutes, then get_section → answers with the real section text + citation.

<!-- TODO: docs/demo.gif — recorded in Claude Desktop -->

What it demonstrates

A complete public-data pipeline, end to end:

Stage	Implementation
Acquisition	Finlex open data REST API — resolves and downloads the newest consolidated (ajantasainen) version of each statute (src/scripts/fetch.ts)
Structuring	Akoma Ntoso (OASIS LegalDocML) XML parsed into a SQLite schema: statute → chapter → section, with amendment labels and full-text search (src/parse.ts, src/scripts/ingest.ts)
Implementation	A Model Context Protocol server (official TypeScript SDK) exposing three tools to any MCP host (src/server.ts)
Verification	15 scripted lookups through the real MCP interface, cross-checked against the live finlex.fi rendering — current accuracy: 15/15, regenerated by npm run verify, enforced in CI

Zero runtime API costs: the server is pure local retrieval. No keys, no external calls, no LLM spend.

Tools

Tool	What it does
search_statutes(query)	Full-text search over the covered statutes; returns sections with citations and snippets. Handles Finnish inflection with stem-prefix matching.
get_section(statute, chapter, section)	Exact text of one pykälä, with formal citation, amendment label ("sellaisena kuin se on laissa 1211/2013"), and any confirmed-but-not-yet-in-force wording explicitly flagged.
list_statute_structure(statute?)	Without arguments: the exact dataset coverage. With a statute: its full table of contents.

Every response ends with the source line: consolidation date, data-fetch date, and the finlex.fi link — so a downstream AI can always disclose how fresh its law is.

Accuracy discipline (the interesting part)

• Scope honesty. v1 covers exactly one statute: Kuluttajansuojalaki (38/1978). The tool descriptions state this coverage as exhaustive, and out-of-scope requests are refused with a pointer to finlex.fi instead of a guess (verified: check #14).
• Pending amendments handled correctly. Finlex consolidations include confirmed future changes (e.g. L 31/2026 rewrites KSL 7:10 effective 20.11.2026). The server returns the wording in force today as primary, and flags the upcoming wording as EI VIELÄ VOIMASSA (verified: check #9).
• No hand-written accuracy claims. VERIFICATION.md is generated by the verification script, which exits non-zero on any failure — CI fails if accuracy drops.

Connect to Claude Desktop

Add to claude_desktop_config.json (Settings → Developer → Edit Config):

{
  "mcpServers": {
    "finlex": {
      "command": "node",
      "args": ["/ABSOLUTE/PATH/TO/finlex-mcp/dist/server.js"]
    }
  }
}

Or run the container (no local Node needed):

{
  "mcpServers": {
    "finlex": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "finlex-mcp"]
    }
  }
}

Any other MCP host works the same way — the server speaks standard MCP over stdio.

Build from source

npm ci
npm run fetch    # download newest consolidations from Finlex open data
npm run ingest   # parse XML -> SQLite (data/finlex.db)
npm run verify   # regenerate VERIFICATION.md against live finlex.fi
npm start        # serve over stdio

Or: docker build -t finlex-mcp . — the image ships a ready-built database from the committed XML snapshot.

Adding a statute is one line in src/config.ts plus npm run fetch && npm run ingest.

Data source & license

• Statute data: Finlex open data (Ministry of Justice / Legal Register Centre), used under CC BY 4.0 as published on avoindata.fi. Finnish statute text itself is exempt from copyright (tekijänoikeuslaki 404/1961 § 9).

• The fetch pipeline identifies itself with a User-Agent (required by the API) and paces requests politely.

• Finlex's consolidations are informational, not the authoritative source of law — the XML itself declares FRBRauthoritative="false". Hence: verify against finlex.fi, and nothing this server returns is legal advice.

• Code: MIT © Anna Sebedach