uk-legal-mcp 0.2.0

UK legal research MCP server — case law, legislation, parliament, bills, votes, committees, citations, HMRC

uk-legal-mcp

A Model Context Protocol server for UK legal research. Connects AI assistants to case law, legislation, parliamentary debates, OSCOLA citation parsing, and HMRC tax data through a single endpoint.

15 tools across 5 modules. One connection. Read-only. No API keys required for 14 of 15 tools.

MCP Client (Claude, Cursor, etc.)
        |
        v
  uk-legal-mcp gateway  (Streamable HTTP)
  +----------------------------------------------------+
  |                                                    |
  |  case_law      TNA Find Case Law API               |
  |  legislation   legislation.gov.uk + i.AI Lex API   |
  |  parliament    Hansard API + Members API            |
  |  citations     OSCOLA regex parser (no network)     |
  |  hmrc          HMRC sandbox/prod + GOV.UK search    |
  |                                                    |
  +----------------------------------------------------+

Quickstart

Connect to the hosted server

Add to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "uk-legal": {
      "type": "streamable-http",
      "url": "https://uk-legal-mcp.fly.dev/mcp"
    }
  }
}

Then try:

• "Search for case law about cycling accidents"
• "Get section 172 of the Companies Act 2006"
• "Parse the citations in: The court applied Donoghue v Stevenson [1932] AC 562 and s.2 Occupiers' Liability Act 1957"
• "What is parliament saying about short selling?"

Run locally

pip install -e .
python -m src.gateway
# Server starts on http://localhost:8000/mcp

Inspect with the MCP Inspector:

npx @modelcontextprotocol/inspector http://localhost:8000/mcp

---

Tools

Case Law

Tool	What it does
case_law_search	Full-text search of UK judgments. Filter by court, judge, party, date range.
case_law_get_judgment	Retrieve full LegalDocML XML for a judgment by TNA URI slug.

Upstream: TNA Find Case Law (Atom/XML). Rate limit: 1,000 req/5 min. Cached 1 hour.

Legislation

Tool	What it does
legislation_search	Search Acts of Parliament and Statutory Instruments via the i.AI Lex API.
legislation_get_toc	Table of contents for an Act — parts, chapters, sections, schedules.
legislation_get_section	Retrieve a specific section with territorial extent, in-force status, and version date.

Upstream: legislation.gov.uk (CLML XML) + i.AI Lex API (JSON). Cached 24 hours.

Note: Always check the extent field. A section may apply to England and Wales but not Scotland or Northern Ireland.

Parliament

Tool	What it does
parliament_search_hansard	Search Hansard debate contributions by exact phrase.
parliament_vibe_check	Assess parliamentary reception of a policy topic. Searches Hansard, then uses LLM sampling to classify sentiment, supporters, opponents, and concerns.
parliament_find_member	Look up an MP or Lord by name. Returns member ID for use with member_debates.
parliament_member_debates	Retrieve a specific member's Hansard contributions, optionally filtered by topic.

Upstream: hansard-api.parliament.uk + members-api.parliament.uk. Not cached (live data).

Citations

Tool	What it does
citations_parse	Extract all OSCOLA citations from free text. Resolves to canonical URLs. Disambiguates bare court codes via LLM sampling.
citations_resolve	Parse and resolve a single citation string to its canonical URL.
citations_network	Fetch a judgment from TNA and map every citation within it — cases, legislation, SIs, EU law.

Self-contained. No external API. Zero network dependency (except citations_network which fetches the judgment XML).

Supported citation formats:

Format	Example
Neutral citation	[2024] UKSC 12
Law report (with or without volume)	[2024] 1 WLR 100, [1932] AC 562
Legislation section	s.47 Companies Act 2006
Statutory Instrument	SI 2018/1234
Retained EU law	Regulation (EU) 2016/679

HMRC

Tool	What it does
hmrc_get_vat_rate	VAT rate lookup for any commodity or service. Static table current as of Autumn Statement 2023.
hmrc_check_mtd_status	Check Making Tax Digital VAT mandate status for a VRN. Requires HMRC OAuth credentials.
hmrc_search_guidance	Search GOV.UK for HMRC guidance documents.

hmrc_get_vat_rate and hmrc_search_guidance require no credentials. hmrc_check_mtd_status requires HMRC_CLIENT_ID and HMRC_CLIENT_SECRET — register at developer.service.hmrc.gov.uk. Defaults to sandbox; set HMRC_API_BASE=https://api.service.hmrc.gov.uk for production.

---

Architecture

src/
  gateway.py            FastMCP gateway — mounts all modules, applies middleware
  deps.py               Shared httpx clients (lifespan-managed) + error formatting
  modules/
    case_law/           TNA Find Case Law (Atom/XML parsing)
    legislation/        legislation.gov.uk (CLML XML) + Lex API (JSON)
    parliament/         Hansard API + Members API (JSON)
    citations/          OSCOLA regex engine (compiled once, lru_cache)
    hmrc/               HMRC OAuth + GOV.UK search (JSON)
tests/
  test_citations.py     35 unit tests — regex patterns, resolution, disambiguation

Each module is a standalone FastMCP instance mounted into the gateway with a namespace prefix (case_law_, legislation_, etc.). All modules share a single httpx client pool via the gateway's lifespan context.

Middleware stack (gateway level):

Middleware	Purpose
RateLimitingMiddleware	50 req/min per client across all modules
ResponseLimitingMiddleware	80,000 char cap (LegalDocML XML can exceed 200k)
ResponseCachingMiddleware	Per-module TTLs on case_law (1hr), legislation (24hr), hmrc (90 days)

---

Deployment

Fly.io

fly auth login
fly launch --name uk-legal-mcp --region lhr
fly deploy

Optional secrets:

fly secrets set HMRC_CLIENT_ID=your_id HMRC_CLIENT_SECRET=your_secret
# For production HMRC (default is sandbox):
fly secrets set HMRC_API_BASE=https://api.service.hmrc.gov.uk

Docker

docker build -t uk-legal-mcp .
docker run -p 8000:8000 uk-legal-mcp

---

Testing

pip install -e '.[test]'  # or: pip install pytest
pytest tests/test_citations.py -v

All 35 citation tests run offline with no API credentials.

---

Upstream APIs and Licences

Source	API	Licence	Auth
TNA Find Case Law	caselaw.nationalarchives.gov.uk	Open Justice Licence	None
legislation.gov.uk	legislation.gov.uk	OGL v3	None
i.AI Lex API	lex.lab.i.ai.gov.uk	OGL v3	None
UK Parliament Hansard	hansard-api.parliament.uk	Open Parliament Licence	None
UK Parliament Members	members-api.parliament.uk	Open Parliament Licence	None
HMRC	test-api.service.hmrc.gov.uk	OGL / commercial terms	OAuth 2.0
GOV.UK Search	www.gov.uk/api/search.json	OGL v3	None

---

Stack

• Python 3.12
• FastMCP v3 (streamable HTTP transport)
• httpx (async HTTP with connection pooling)
• lxml (LegalDocML and CLML XML parsing)
• Pydantic v2 (input validation, output serialisation)
• Fly.io (London region, auto-stop/start)