io.github.matematicsolutions/gb-eli-mcp

gb-eli-mcp

An MCP server for legislation.gov.uk, The National Archives' official portal for United Kingdom legislation. It searches and retrieves Acts of Parliament, UK Statutory Instruments, and the equivalent instruments of the Scottish Parliament, Senedd Cymru/Welsh Parliament and Northern Ireland Assembly, with persistent identifiers and verifiable citations.

Part of the MateMatic eu-legal-mcp production line: the UK counterpart of the Polish sejm-eli-mcp and the German de-eli-mcp, built on the same architecture and citation contract against the UK's own source.

No native ELI. legislation.gov.uk does not publish a native /eli/ namespace (confirmed live: GET /eli/ukpga/2018/12 returns 404), even though its own persistent-identifier scheme predates and is closely related to ELI - the UK is widely credited with pioneering the URI-based legislation-identifier concept that ELI later formalised EU-wide. eli_uri therefore carries the UK's own stable id URI (https://www.legislation.gov.uk/id/{type}/{year}/{number}) instead of a fabricated ELI path - the same disclosure pattern used by this factory's nl-eli-mcp and se-eli-mcp. See CONSTITUTION.md Art. 4.

Licence. Content is published under the Open Government Licence v3.0 (confirmed live from the site's own /help page), which permits copying, publishing and adapting with attribution. This connector only relays that public content, with a source_url on every response.

The nine tools

GOV.UK coverage (added v0.3.0, feature-003)

One upstream, many institutions: gb_search_govuk filters by document_type. Live-verified totals (2026-07-07, from the Search API's own total/facet fields - probe: https://www.gov.uk/api/search.json?count=0&facet_content_store_document_type=1000):

See SOURCES.md for the full per-source ledger, including what was scouted and deliberately rejected (ICO, FCA, IAC) and why.

Every response carries the contract: eli_uri (e.g. https://www.legislation.gov.uk/id/ukpga/2018/12), human_readable_citation (e.g. Data Protection Act 2018 c. 12), and source_url. Case-law responses carry the same-spirit contract (human_readable_citation, source_url, dataset_note) - see CONSTITUTION.md Art. 5.

Install

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/gb-eli-mcp
/plugin install gb-eli-mcp@gb-eli-mcp

As a standalone server, from PyPI (uvx gb-eli-mcp), or from source:

cd gb-eli-mcp
pip install -e .

Configure (Claude Code / any MCP client)

Copy .mcp.json.example and adjust if needed:

{
  "mcpServers": {
    "gb-eli-mcp": { "command": "gb-eli-mcp" }
  }
}

Windows 11 with Smart App Control

Smart App Control blocks unsigned executables, which covers uvx.exe, pip.exe and the gb-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 gb-eli-mcp
python -m gb_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 gb_eli_mcp.

{ "mcpServers": { "gb-eli-mcp": { "command": "python", "args": ["-m", "gb_eli_mcp"] } } }

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

Environment:

• GB_ELI_BASE_URL - default https://www.legislation.gov.uk
• GB_ELI_CASELAW_BASE_URL - default https://caselaw.nationalarchives.gov.uk
• GB_ELI_GOVUK_BASE_URL - default https://www.gov.uk
• GB_ELI_CACHE_DIR - default ~/.matematic/cache/gb-eli
• GB_ELI_AUDIT_DIR - default ~/.matematic/audit

No API key. legislation.gov.uk is keyless.

Governance

• Public data only - read-only against legislation.gov.uk, Find Case Law and GOV.UK; no client data leaves the machine beyond search parameters.
• Audit log - every tool call appends one JSON line to ~/.matematic/audit/gb-eli-mcp.jsonl.
• Network - the server talks to legislation.gov.uk, caselaw.nationalarchives.gov.uk, www.gov.uk and the local filesystem. Once, on first use, it also fetches a small configuration file (gb-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. GB_ELI_RUNTIME_URL="" turns it off; the Claude plugin ships with it off. No LLM provider, no other telemetry.
• Verifiable citations - every response is independently checkable via source_url.

See CONSTITUTION.md (the binding rules) and DISCOVERY.md (the live API probe).

Tests

pip install -e ".[dev]"
pytest tests/test_instructions_drift.py -v   # offline
pytest tests/test_citations_case_law.py -v   # offline
pytest tests/test_citations_govuk.py -v      # offline
pytest tests/test_smoke.py -v                # hits live legislation.gov.uk
pytest tests/test_smoke_case_law.py -v       # hits live caselaw.nationalarchives.gov.uk
pytest tests/test_smoke_govuk.py -v          # hits live www.gov.uk

Licence

Apache-2.0. (c) Matematic Solutions / Wieslaw Mazur.

Note: the code in this repository is Apache-2.0. The legislation content fetched at runtime from legislation.gov.uk remains Crown copyright, published under the Open Government Licence v3.0 - not relicensed by this project.