LexAPI

LexAPI MCP

Model Context Protocol server for LexAPI — EU law for AI assistants: EUR-Lex legislation parsed to article level, CJEU case law, the typed citation graph, and semantic search (including the law as in force on a past date). Works with Claude, Cursor, VS Code and any other MCP client.

Ask your assistant *"what does Article 17 GDPR require?"*, *"which acts amended REACH?"* or *"what were the own-funds requirements for banks in June 2019?"* — the model calls LexAPI and answers from the source text, with CELEX citations.

You need a LexAPI account. With the hosted server you just sign in with LexAPI from your MCP client; with the npm package (or if you prefer), use an API key from lex-api.com/dashboard. There is a FREE plan, no card required, with enough credits to try the read tools; current allowances are on lex-api.com/pricing.

Connect to the hosted server (sign in with LexAPI)

The server is hosted at `https://mcp.lex-api.com/v1` (Streamable HTTP). Add that URL to your client and sign in with your LexAPI account when it asks — no key to copy. You see a LexAPI consent page listing what the connection can do; calls are billed to your plan exactly like your own API key, and you can disconnect the app at any time under *Dashboard → Connected apps* (that revokes it immediately).

claude.ai and Claude Desktop

*Settings → Connectors → Add custom connector*, name it LexAPI, URL https://mcp.lex-api.com/v1, then *Connect* and sign in. Connectors added on claude.ai are also available in Claude Desktop (same account).

Claude Code

claude mcp add --transport http lexapi https://mcp.lex-api.com/v1

Then run /mcp in Claude Code and choose *Authenticate* for lexapi; your browser opens the LexAPI sign-in.

Other MCP clients

Any client that implements MCP authorization (OAuth 2.1 with protected-resource discovery) connects the same way: point it at https://mcp.lex-api.com/v1. The server answers an unauthenticated request with 401 and WWW-Authenticate: Bearer … resource_metadata="https://mcp.lex-api.com/.well-known/oauth-protected-resource/v1"; the client discovers LexAPI (https://lex-api.com) as the authorization server from there.

With an API key instead

Clients without OAuth support — or scripts — send a key from the dashboard as Authorization: Bearer lex_... (or x-api-key: lex_...):

claude mcp add --transport http lexapi https://mcp.lex-api.com/v1 --header "Authorization: Bearer lex_..."

Run it locally (npm, API key)

Claude Desktop (local)

Add to claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/claude_desktop_config.json):

{

"mcpServers": { "lexapi": { "command": "npx", "args": ["-y", "@lexapi/mcp"], "env": { "LEXAPI_API_KEY": "lex_..." } } } }

Restart Claude Desktop.

Claude Code (local)

claude mcp add lexapi --env LEXAPI_API_KEY=lex_... -- npx -y @lexapi/mcp

Cursor, VS Code and other stdio clients

Run npx -y @lexapi/mcp with LEXAPI_API_KEY in the environment (Cursor: ~/.cursor/mcp.json; VS Code: .vscode/mcp.json; same command / args / env shape as above).

The npm package needs Node.js 20 or newer. It uses an API key; signing in with LexAPI is a feature of the hosted server.

Tools

Every call is billed from your LexAPI credit pool exactly like the REST endpoint it wraps; each tool's description states its cost so the model can see it.

National law

lex_national_coverage, lex_list_national_documents, lex_get_national_document, lex_national_semantic_case_law and lex_national_semantic_legislation cover member-state legislation and case law alongside the EU_LAW tools above. A country can be registered on LexAPI before it is made available to customers — always call lex_national_coverage first; the other tools answer an error for a country that isn't live yet. The citation-graph tools (lex_cited_by, lex_cites, lex_citation_network, lex_citation_path, lex_related, lex_citation_stats) accept national document ids directly (e.g. "AT-NOR-12345") and an includeNational option to pull in national neighbours — BUSINESS, SCALE and ENTERPRISE only, 403 below that. National results have the same fields in every country (LexAPI API 2.8.0): documentKind (act | decision) everywhere, and on a decision court, chamber, caseNumbers and citedNorms — whatever the source calls them. Every national result carries attribution (the official source and its licence, e.g. RIS, gesetze-im-internet.de, Normattiva, Légifrance/Judilibre, the Rechtspraak open data) — show it to the user alongside anything quoted. On FREE/STARTER/PROFESSIONAL plans, national-law calls also draw from a separate monthly allowance (reported as allowance on each response); BUSINESS and higher have no separate limit. A document its source withdrew (a takedown, a pseudonymisation fix) answers a distinct error — nothing of it is served, not even the title; the model is told not to retry and to drop any cached copy.

How results are shaped for models

• Compact output. Responses drop envelopes and duplicate legacy fields. Documents keep their metadata, textAvailability (why text is missing, which languages exist, a pointer to the latest consolidated version) and language-fallback labels.
• Large documents. lex_get_document returns the whole body when it fits maxChars (default 40,000 characters), otherwise an outline (article ids, section tree, counts). Fetch an article with articleId or parts with include; long parts continue with offset.
• Consolidated texts are not authentic. Consolidated versions carry consolidated: true, consolidatedAsOf, baseCelex and a note: quote them, cite the act as published in the Official Journal.
• `asOf`. Each legislation hit says whether it carries the version in force on that date (asOfResolved, asOfVersion); unresolved hits keep the current text with an asOfReason, and the response warns about them.
• Errors say what to do. A 402 states the credits needed, the credits left and the reset date; a 429 says how long to wait.

Configuration

The key is sent only as the x-api-key header to LexAPI; it is never logged or included in tool output. A LEXAPI_API_KEY containing whitespace or control characters (e.g. a multi-line paste) is rejected at startup.

Hosting the HTTP server

npm run start:http (or the Dockerfile) runs the Streamable HTTP transport (POST /v1, GET /health). Self-hosted, it accepts LexAPI API keys (Authorization: Bearer lex_… or x-api-key: lex_…); a request without one gets 401. A value that cannot be an API key (it contains a . or is longer than 8192 characters) is answered 401 and never forwarded.

Sign in with LexAPI is a feature of the hosted server at https://mcp.lex-api.com/v1: it needs an OAuth client registered with LexAPI, so a self-hosted copy runs with API keys only. The OAuth-related settings in src/oauth/config.ts (LEXAPI_OAUTH_*, LEXAPI_MCP_*) are for that deployment; the server refuses to start if they are set incompletely.

`/health` returns status