UK Legislation MCP Server

A local MCP server providing real-time access to UK statute data from legislation.gov.uk.

Overview

Property	Value
Source	legislation.gov.uk (Open Government Licence v3.0)
API key	Not required
Transport	stdio (runs as a local process)
Location	mcp-servers/uk-legislation/src/index.ts
Cache	24-hour in-memory, 500-entry LRU
Fetch timeout	30 seconds

Running the Server

cd mcp-servers/uk-legislation
npm install
npm run dev     # start the server (tsx src/index.ts)

For production builds:

npm run build   # compiles to dist/
npm test        # build + run tests

Automatic Startup

When configured in .mcp.json, Claude Code starts the server automatically when a skill needs it. You do not need to start it manually.

Tools

The server exposes 6 tools:

1. search_legislation

Search UK legislation by title keywords.

Parameter	Type	Required	Description
title	string	Yes	Search keywords for the legislation title
type	string	No	Filter by legislation type (e.g., ukpga, uksi)
year	number	No	Filter by year

Returns: Up to 20 results, each with title, type, year, number, and URI.

Example: search_legislation("Companies Act", type="ukpga")

2. lookup_statute

Get full metadata and text of a specific Act or Statutory Instrument.

Parameter	Type	Required	Description
type	string	Yes	Legislation type (e.g., ukpga, uksi)
year	number	Yes	Year of the legislation (1200-2100)
number	number	Yes	Number within that year

Returns: Title, enacted date, extent, parts count, provisions count, and full text.

Example: lookup_statute(type="ukpga", year=2006, number=46)
         → Companies Act 2006

3. lookup_section

Get a specific section of an Act, including amendment notes.

Parameter	Type	Required	Description
type	string	Yes	Legislation type
year	number	Yes	Year
number	number	Yes	Number
section	string	Yes	Section number (e.g., "1", "10A")

Returns: Section text and commentary references (amendment notes with ID, type, and description).

Example: lookup_section(type="ukpga", year=2006, number=46, section="172")
         → Companies Act 2006, s.172 — Duty to promote the success of the company

4. check_in_force

Check whether a statute or specific provision is currently in force.

Parameter	Type	Required	Description
type	string	Yes	Legislation type
year	number	Yes	Year
number	number	Yes	Number
section	string	No	Specific section to check

Returns: Status per provision, categorised as:

• In Force -- provision is currently active, with commencement date
• Not Yet In Force -- provision has a future commencement date
• Prospective -- provision is enacted but awaiting commencement order
• Repealed -- provision has been repealed

Commencement Complexity

Some Acts commence in stages over years. If no explicit commencement data is found in the XML, the tool recommends checking the Act's commencement section or related Commencement Orders (SIs).

5. check_amendments

Get amendments affecting a specific statute from the legislation.gov.uk changes feed.

Parameter	Type	Required	Description
type	string	Yes	Legislation type
year	number	Yes	Year
number	number	Yes	Number

Returns: Up to 30 amendments, each with:

• Amending instrument (the SI or Act that made the change)
• Affected provision (the specific section amended)
• Effect type (e.g., substituted, inserted, repealed)
• Date of the amendment

Example: check_amendments(type="ukpga", year=1998, number=42)
         → Amendments affecting the Human Rights Act 1998

6. get_extent

Check the territorial extent of UK legislation -- which jurisdictions it applies to.

Parameter	Type	Required	Description
type	string	Yes	Legislation type
year	number	Yes	Year
number	number	Yes	Number

Returns: Overall extent and provision-level breakdown with decoded extent codes:

Code	Jurisdiction
E+W+S+N.I.	England, Wales, Scotland, Northern Ireland (UK-wide)
E+W+S	England, Wales, Scotland (Great Britain)
E+W	England and Wales
E	England only
W	Wales only
S	Scotland only
N.I.	Northern Ireland only

Legislation Types

The server supports 15 legislation types:

Code	Description
ukpga	UK Public General Acts
uksi	UK Statutory Instruments
asp	Acts of the Scottish Parliament
asc	Acts of Senedd Cymru
anaw	Acts of the National Assembly for Wales
mwa	Measures of the National Assembly for Wales
nia	Northern Ireland Acts
nisi	Northern Ireland Orders in Council
nisr	Northern Ireland Statutory Rules
ssi	Scottish Statutory Instruments
wsi	Wales Statutory Instruments
ukla	UK Local Acts
ukcm	UK Church Measures
ukci	UK Church Instruments
uksro	UK Statutory Rules and Orders

Caching

The server maintains a 24-hour in-memory cache to reduce load on legislation.gov.uk and improve response times.

Property	Value
TTL	24 hours
Max entries	500
Eviction	LRU (oldest entry removed when full)
Scope	Per server process (resets on restart)

Cache Behaviour

Cache hits are logged to stderr as [uk-legislation] Cache hit: <url>. On a fresh start, the first request for each statute will be slower (network fetch), but subsequent requests within 24 hours return instantly.

Error Handling

Scenario	Behaviour
Statute not found	Returns Error: Not found: <url>
Network timeout	Returns Error: Request timed out after 30s: <url>
HTTP error	Returns Error: HTTP <status> fetching <url>
Amendments feed unavailable	Returns helpful message suggesting the changes feed may not be available for that item