Uk Legislation Mcp Server

io.github.cyanheadsPublished by GitHub account cyanheadsv0.2.1Updated Oct 29, 2026

Search and read UK legislation at any date, resolve citations, list amendments, track changes.

VerifiedStreamable HTTPWeb executableWeb Search & ScrapingKnowledge & Memory

Overview

AI-generated overview

Reads the UK statute book from legislation.gov.uk: search legislation, read provisions at any date, resolve citations, list amendments and track changes.

What you can do
  • Search and list legislation by full text, title, type and year, filtered by extent and point in time
  • Read an item or provision as revised, as enacted, or as it stood on a date, with editorial status and unapplied effects
  • List the effects (amendments, repeals, commencements, modifications) made to or by an item
  • Track the legislation.gov.uk Publication Log over a window of up to 31 days
  • Resolve citations, short titles and legislation.gov.uk URIs to canonical items and provisions
  • Decode type codes, extents, version keywords and citation forms offline
When to use it
Useful when an assistant needs to answer questions about UK, Scottish, Welsh or Northern Irish legislation, check whether a provision is in force or what it said on a given date, trace what amended it, or monitor recent publication changes.
Requirements
Either the hosted HTTP endpoint or a local process via npx (Node.js) or Docker; no API key or account. Set UK_LEGISLATION_CONTACT to an email or URL on shared deployments, as legislation.gov.uk's fair use policy asks clients to identify themselves. Network access to legislation.gov.uk is required.
Before you install
Read-only against legislation.gov.uk; no writes or payments. Revised text is an editorial consolidation that can lag behind amendments, so editorial status and unapplied effects should be checked before relying on it. Requests are rate-limited by a shared queue, and the hosted instance paces all callers at one upstream request per second. Legislation text and notes are third-party data, not instructions.

Installation

In SourceWeft

  1. Open Uk Legislation Mcp Server in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/io.github.cyanheads%2Fuk-legislation-mcp-server/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "uk-legislation": {
      "type": "http",
      "url": "https://uk-legislation.caseyjhand.com/mcp"
    }
  }
}

README

@cyanheads/uk-legislation-mcp-server

Search and read UK legislation at any date, resolve citations, list amendments, track changes via MCP. STDIO or Streamable HTTP.

6 Tools • 1 Resource

Overview

The UK statute book from legislation.gov.uk: primary, secondary, and EU-origin legislation for the UK, England, Scotland, Wales, and Northern Ireland. Resolve citations, search by text or title, read any provision as it stands today, as enacted, or on a past date, and track amendments. No API key required.

Tools

ToolDescription
uklaw_search_legislationSearch by full text or title, or list by type and year, filtered by extent and point in time
uklaw_get_documentRead an item or provision as revised, as enacted or made, or on a date, with its editorial status and unapplied effects
uklaw_get_amendmentsList the effects (amendments, repeals, commencements, modifications) recorded against an item or made by it
uklaw_track_changesRead the legislation.gov.uk Publication Log for a window of up to 31 days
uklaw_lookup_citationResolve a citation, short title, or legislation.gov.uk URI to the canonical item and provision
uklaw_list_referenceDecode type codes, extents, version keywords, annotation letters, citation forms, and other vocabulary, offline

Resources

ResourceDescription
skill://uk-legislation-guide/SKILL.mdAgent Skill covering how to decide with the uklaw_* tools whether a provision is in force and current, its text on a date, what amended or commenced it, and what changed since a date

The skill is served over MCP through the Agent Skills extension (io.modelcontextprotocol/skills, skill://{+path} template) and ships in skills/ in the npm package, the Docker image, and the .mcpb bundle. The tools do not depend on it.

Capability reference

uklaw_search_legislation tool

  • text (full text: AND/OR, "quoted phrases", stemming) and/or title (every word must occur), or neither to list by type and year; limit 1–50 (default 20) with page
  • Filters: types (codes such as ukpga, uksi, eur, or the groups all, primary, secondary, eu-origin, draft; default all, which excludes drafts), year or year_from / year_to (1267–2100), extent (england, wales, scotland, ni) with extent_match (applicable or exact), and as_of (YYYY-MM-DD); extent and as_of cannot be combined
  • Each result carries the item path to pass to uklaw_get_document; has_more flags another page, and title searches and listings add facets (type counts and the newest 25 years)

uklaw_get_document tool

  • item is a full path (ukpga/2018/12, uksi/2019/419, eur/2016/679, regnal ukpga/Eliz2/3-4/19) or a legislation.gov.uk URI; provision a path (section/45/2/f, schedule/2/paragraph/3) or shorthand (s. 45(2)(f), Sch. 2 para. 3); version current (default), enacted (or made, adopted, created), or a YYYY-MM-DD date; language en or cy
  • kind is full (Markdown text with its annotations), outline (provision paths to read next, 100 per call from outline_offset), or pdf_only (links.pdf); text over 20,000 characters, or an item with more than 25 leaf provisions, comes back as an outline (a provision with no smaller provisions to list is returned whole up to 40,000 characters and cut past that, with a notice linking the full text), and match_text lists an item's provisions that contain a term
  • editorial (document_status, outstanding_effects, caveat) and unapplied_effects (the first 20, at item or provision level; a provision read also lists the effects on its enclosing provisions and, on full text, the provisions inside it, and says when it could not check them) show how far the revised text can be relied on; version.available lists the versions to pass as version

uklaw_get_amendments tool

  • item full or partial (uksi, ukpga/2018); direction affected (default: changes made to it) or affecting (changes it makes); filters counterpart (the other item, full or partial), status (all, unapplied, applied; default all), and provision (needs a full item; scans up to 1,500 effects per call)
  • limit 1–100 (default 20), continued with next_cursor; each effect names both sides with their provisions, in_force dates, applied / outstanding, and notes; total counts effects before the provision filter, and scan reports its coverage
  • Pre-1963 Acts are queried by calendar year (ukpga/1925/20) and drafts are not indexed: both fail as regnal_item / draft_item, with the route to take instead

uklaw_track_changes tool

  • start_date (required) and end_date (defaults to start_date), a window of at most 31 days; filters content_type (legislation, changes, draft, associated-documents), direction (with changes only), category (primary, secondary, eu-origin; with legislation or associated-documents only), item, new_only, and event (published, withdrawn)
  • limit 1–80 (default 40), continued with next_cursor; mode is day_walk (days newest first, up to 4 upstream requests per call) or item_log (a full item path reads that item's own log and reports read_back_to)
  • A changes event carries no effect detail: uklaw_get_amendments on its item has it

uklaw_lookup_citation tool

  • One citation of up to 300 characters: a numbered citation, a short title, or a legislation.gov.uk URI, optionally with a provision (forms below)
  • Returns the canonical item path, plus provision_found for a cited provision, checked against the current version; a miss or an ambiguous title is found: false with guidance or up to 20 candidates, not an error
FormExamplesResolves to
UK Act by chapter2018 c. 12ukpga/2018/12; before 1963 the calendar year is searched and the regnal candidates returned
Act of the Northern Ireland Assembly2016 c. 5 (N.I.)nia/2016/5
UK Statutory InstrumentS.I. 2019/419, SI 2019 No. 419, S.I. 2002/808 (W. 89)uksi/2019/419; alternative series numbers are ignored, and Welsh and NI SIs canonicalize to wsi / nisi
Scottish Statutory InstrumentS.S.I. 2020/123ssi/2020/123
Northern Ireland Statutory RuleS.R. 2020/12, S.R. 2020 No. 12nisr/2020/12
Scottish and Welsh Acts and Measures2020 asp 13, asp 2020/13, 2016 anaw 1, 2021 asc 1, 2010 nawm 1asp/2020/13, anaw/2016/1, asc/2021/1, mwa/2010/1
EU-origin legislationRegulation (EU) 2016/679, Regulation (EC) No 1535/2003, Directive 95/46/EC, Decision (EU) 2019/419; the issuing body may lead (Council Regulation (EC) No 1/2003)eur/2016/679, eur/2003/1535 (pre-2015 numbering is number/year), eudr/1995/46, eudn/2019/419
Defined nameUK GDPReur/2016/679
legislation.gov.uk URIhttps://www.legislation.gov.uk/ukpga/2018/12/section/45Split into item, provision, and version
Short titleData Protection Act 2018, Human Rights Act 1998 (c. 42)Resolved by title and year; a trailing chapter resolves the Act by number when the title does not

Any form can end with a provision (s. 45(2)(f), section 45, reg. 5, art. 28(3), r. 7, r. 3.4, Sch. 2 para. 3, Pt 3) or start with one followed by "of" or "of the": section 45 of the Data Protection Act 2018. uklaw_list_reference topic citation_formats returns the same list.

uklaw_list_reference tool

  • topic: types, type_groups, extents, versions, document_status, annotation_types, effects, provision_paths, citation_formats, publication_log, coverage, or attribution
  • Offline, with no request to legislation.gov.uk; each entry is a key, label, description, and optional details

skill://uk-legislation-guide/SKILL.md resource

  • Markdown with YAML frontmatter: scope, identifier sources, the gates for in-force status, revised-text lag, container effects, dated reads, and date semantics, and workflows for commencement, point-in-time text, amendment history, and changes since a date
  • Listed in resources/list; the skill://{+path} template reads any file under it

Features

Built on @cyanheads/mcp-ts-core: stdio and Streamable HTTP transports, pluggable auth (none / jwt / oauth), swappable storage (in-memory, filesystem, Supabase, Cloudflare KV/R2/D1), structured logging with optional OpenTelemetry tracing.

legislation.gov.uk-specific:

  • Keyless client for legislation.gov.uk's API: CLML XML for documents, Atom feeds for search, effects, and the Publication Log
  • Follows legislation.gov.uk's fair use policy: an identifying User-Agent on every request, one process-wide queue that spaces request starts (1 second apart by default) and adopts a longer robots.txt crawl delay set for this server, up to 60 seconds, and at most 4 upstream requests per tool call within a 45-second deadline
  • Process-wide response cache, with lifetimes taken from upstream max-age (capped at one hour) and If-Modified-Since revalidation
  • Citation shorthand (s. 45(2)(f), reg. 5, Sch. 2 para. 3) normalized to provision paths; pre-1963 regnal paths and Welsh-language text (language: "cy") supported
  • PDF-only items are linked, never fetched, as legislation.gov.uk's robots.txt requires

Agent-friendly output:

  • Every document read returns its editorial status with the text (editorial.document_status, caveat, outstanding_effects) and the unapplied_effects touching it, so the caller can tell when the revised text is behind on amendments
  • uklaw_lookup_citation returns a miss as found: false with guidance or candidates, not as an error
  • Each tool's typed error reasons (provision_not_found, version_not_found, regnal_item, …) carry a recovery hint naming the next call
  • Every response that returns legislation includes attribution, the licence lines its content needs (see License)
  • Upstream text is treated as data: legislation text, annotations, and effect notes are blockquoted in content[], inline values are escaped, and URIs are percent-encoded

Getting started

Connect to the hosted instance, no install:

sh
claude mcp add --transport http uk-legislation-mcp-server https://uk-legislation.caseyjhand.com/mcp

Every caller of the hosted instance shares one request queue, paced at one legislation.gov.uk request per second under its fair use policy. For sustained use, run your own instance.

Or run it locally:

sh
claude mcp add uk-legislation-mcp-server -- npx -y @cyanheads/uk-legislation-mcp-server

For other clients, add this to the MCP config file:

json
{  "mcpServers": {    "uk-legislation-mcp-server": {      "command": "npx",      "args": ["-y", "@cyanheads/uk-legislation-mcp-server"]    }  }}

No API key or account is needed. The legislation.gov.uk fair use policy asks non-browser clients to identify themselves, so set UK_LEGISLATION_CONTACT to an email or URL when you run a shared deployment. For Docker or a source build, see Running the server.

Configuration

VariableDescriptionDefault
UK_LEGISLATION_CONTACTEmail or URL appended to the User-Agent so legislation.gov.uk can reach the operator. Set it on shared deployments.none
UK_LEGISLATION_MIN_REQUEST_GAP_MSMinimum gap between upstream request starts, in ms, across the process; 250 at least. A longer robots.txt crawl delay for this server's User-Agent raises it. Replicas sharing one User-Agent divide the fair use limit, so use at least 250 ms × replica count.1000
UK_LEGISLATION_CACHE_MAX_MBResponse cache size bound, in MB (8–1024).64
MCP_TRANSPORT_TYPETransport: stdio or http.stdio
MCP_HTTP_PORTHTTP server port.3010
MCP_HTTP_HOSTHTTP server host.127.0.0.1
MCP_SESSION_MODEHTTP session mode: stateless, stateful, or auto. .env.example and the Docker image set stateless.auto
MCP_AUTH_MODEAuthentication: none, jwt, or oauth.none
MCP_LOG_LEVELLog level (debug, info, warning, error, etc.).info
LOGS_DIRDirectory for log files (Node.js only).<app-root>/logs
OTEL_ENABLEDEnable OpenTelemetry.false

See .env.example for the full list of optional overrides.

Running the server

Local development

Requires Bun v1.4.0 or higher (or Node.js v24+).

  • Clone and install:

    sh
    git clone https://github.com/cyanheads/uk-legislation-mcp-server.gitcd uk-legislation-mcp-server && bun installcp .env.example .env   # optionally set UK_LEGISLATION_CONTACT

  • Build and run the production version:

    sh
    # One-time buildbun run rebuild
# Run the built serverbun run start:http# orbun run start:stdio

  • Run checks and tests:

    sh
    bun run devcheck  # Lints, formats, type-checks, and morebun run test      # Runs the test suite

Docker

sh
docker run --rm -p 3010:3010 ghcr.io/cyanheads/uk-legislation-mcp-server:latest

The image defaults to HTTP transport, stateless session mode, and logs to /var/log/uk-legislation-mcp-server. To run it over stdio from an MCP client, use "command": "docker" with "args": ["run", "-i", "--rm", "-e", "MCP_TRANSPORT_TYPE=stdio", "ghcr.io/cyanheads/uk-legislation-mcp-server:latest"]. To build locally, docker build -t uk-legislation-mcp-server .; OpenTelemetry peer dependencies are installed by default — build with --build-arg OTEL_ENABLED=false to omit them.

Project structure

DirectoryPurpose
src/index.tscreateApp() entry point: registers the six tools; setup() reads robots.txt and builds the pacer, response cache, client, and service.
src/configServer-specific environment variable parsing and validation with Zod.
skills/The published uk-legislation-guide Agent Skill, served as an MCP resource via createApp({ skills: 'skills' }).
src/mcp-server/tools/definitionsTool definitions (*.tool.ts), plus the shared input/output schemas and Markdown rendering helpers.
src/services/legislationlegislation.gov.uk service layer: HTTP client, response cache, citation and provision-path parsing, CLML and Atom parsers, reference data, attribution.
tests/Unit tests mirroring src/, run against recorded CLML and Atom fixtures.

Development guide

See CLAUDE.md for development guidelines and architectural rules. The short version:

  • Handlers throw, framework catches — no try/catch in tool logic
  • Use ctx.log for logging and ctx.fail with a declared reason for expected failures
  • Register new tools in allToolDefinitions in src/mcp-server/tools/definitions/index.ts
  • Wrap external API calls: validate raw → normalize to domain type → return output schema; never fabricate missing fields

Contributing

Issues are welcome. Run checks and tests before submitting:

sh
bun run devcheckbun run test

License

This project is licensed under the Apache 2.0 License. See the LICENSE file for details.

Legislation content from legislation.gov.uk is © Crown and database right, licensed under the Open Government Licence v3.0. EU-origin items also carry a European Union credit (© European Union, 1998-2020, re-used under Commission Decision 2011/833/EU), and pre-1987 statutory instruments contributed to legislation.gov.uk by Westlaw UK carry a Westlaw credit. Every tool that returns legislation lists the lines that apply to its content in attribution.

Source: README.md at commit d2b7906

Tools

6

uklaw_search_legislation

Search UK legislation

Search the UK statute book on legislation.gov.uk by full text or title, or list legislation by type and year, filtered by geographical extent and point in time. Full-text search ranks by relevance; title searches and type/year listings run newest year first and carry type and year counts (facets) to narrow with. Each result gives the item path to pass to uklaw_get_document. For a known citation or short title, uklaw_lookup_citation is cheaper and exact.

Parameterspagetextyearas_oflimittitletypesextentyear_toyear_fromextent_match

uklaw_get_document

Read UK legislation text

Read one item or one provision of UK legislation from legislation.gov.uk — as it stands now (revised), as enacted/made, or as it stood on a date — in Markdown, with its editorial status, annotations (the applied amendment history), the unapplied effects touching it, the versions available, and attribution. Provision-level reads are the main path; an item-level read returns the whole text only for small items and otherwise an outline of provision paths to read next. With match_text (item level), returns the provisions whose text matches. Revised text is an editorial consolidation that can lag: read editorial.caveat and unapplied_effects before relying on it, and use uklaw_get_amendments for every recorded effect on an item, applied or not.

Parametersitemrequiredversionlanguageprovisionmatch_textoutline_offset

uklaw_get_amendments

List amendments to or by legislation

List the effects — amendments, repeals, revocations, commencements, modifications — recorded against an item (direction affected) or made by an item (direction affecting), from legislation.gov.uk's changes feeds. Filter by the other item (counterpart), by applied status (unapplied = the outstanding work on the revised text), and by provision. item may be partial (ukpga/2018 = all effects on 2018 Acts). Each effect names both sides with provision links, in-force dates, and why it is not applied. For the applied history of one provision in prose, read its annotations with uklaw_get_document.

Parametersitemrequiredlimitcursorstatusdirectionprovisioncounterpart

uklaw_track_changes

Track legislation.gov.uk publications

Read the legislation.gov.uk Publication Log for a date window of up to 31 days: new items, new revised versions, newly recorded effects, and withdrawals, newest first — the compliance-monitoring view of "what changed". Filter by content type, effect direction, category, an item or type/year, first-time items only, or event. With a full item path it reads that item's own log, usually in one call; otherwise it walks the window day by day, newest first, so a broad window may need several calls. A changes event carries no effect detail — uklaw_get_amendments with that item has it. Continue with next_cursor.

Parametersitemeventlimitcursorcategoryend_datenew_onlydirectionstart_daterequiredcontent_type

uklaw_lookup_citation

Resolve a legislation citation

Resolve a citation or short title to the canonical legislation.gov.uk item and provision: "Data Protection Act 2018 s. 45", "2018 c. 12", "S.I. 2019/419", "S.S.I. 2020/123", "S.R. 2020/12", "2020 asp 13", "Regulation (EU) 2016/679 art. 28", a legislation.gov.uk URI, or a short title. Returns the item path to pass to uklaw_get_document, and when a provision is given, whether it exists in the current version. A miss or an ambiguous title is a result with found false plus guidance or candidates, not an error. To find legislation by topic or by partial title words rather than a known citation, use uklaw_search_legislation.

Parameterscitationrequired

uklaw_list_reference

List legislation reference vocabulary

Decode the vocabulary the other uklaw_* tools take and return: legislation type codes (ukpga, uksi, eur, …) with their labels, categories and enacted keywords; type groups; extents; version keywords; document status; annotation letters (F, C, I, M, E, P, X); effect record fields; provision path forms and shorthand; accepted citation formats; Publication Log vocabulary and read modes; data coverage; and the attribution lines. Offline — no request to legislation.gov.uk.

Parameterstopicrequired

Version history

4
  1. v0.2.1LatestOct 29, 2026
  2. v0.1.3Oct 25, 2026
  3. v0.1.2Oct 9, 2026
  4. v0.1.1Sep 27, 2026

Score

100% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts