@registrum/mcp

Registrum MCP Server

UK company data in your AI agent — without building Companies House plumbing.

No Companies House developer account, no rate-limit handling, no iXBRL parsing. Works in Claude Desktop, Claude Code, Cursor, and any MCP-compatible client.

Try it now — no signup, no key, no install

Point your client at the hosted endpoint and every tool answers with real data:

https://registrum.co.uk/api/mcp

{
  "mcpServers": {
    "registrum": {
      "url": "https://registrum.co.uk/api/mcp"
    }
  }
}

That is the whole setup. Ask it "Who ultimately owns Rolls-Royce Holdings?" and it will trace the ownership chain.

The free anonymous tier is generous on the everyday tools and deliberately small on the expensive ones — a couple of ownership-chain traces and financial statements per day, which is enough to see exactly what comes back before you decide anything. When you reach a cap, the tool tells you so and points at a free key; nothing silently degrades.

Why this instead of the Companies House API directly

Companies House publishes the raw register for free, and you can absolutely call it yourself. What you then own is the plumbing:

Doing it yourself	With Registrum
Register for a CH developer key, manage OAuth	Nothing, or one REGISTRUM_API_KEY
600 requests/5min, and you handle the 429s	Server-side throttling on a higher negotiated budget
Accounts arrive as iXBRL documents you must parse	get_financials returns turnover, net assets, profit/loss as numbers
PSC control types are raw codes	Decoded to plain English
Ownership chains: recurse yourself, handle cycles	get_psc_chain returns the resolved tree with termination reasons
Director networks: N+1 queries across appointments	get_network traverses to depth 2
Retry, cache, and survive CH outages yourself	24h/7d caching, circuit breaker, stale-while-revalidate

Other Companies House MCP servers make you bring your own CH key and hand back the raw response. This one does the enrichment.

Running it with your own key

Use a key when you want the anonymous caps lifted, or when you would rather run the server locally than call ours.

Claude Desktop — ~/.claude/claude_desktop_config.json Cursor — .cursor/mcp.json (per project) or ~/.cursor/mcp.json (global)

{
  "mcpServers": {
    "registrum": {
      "command": "npx",
      "args": ["-y", "@registrum/mcp"],
      "env": { "REGISTRUM_API_KEY": "reg_live_..." }
    }
  }
}

Get a free key — no card.

Tools

Tool	What you get
search_company	Find a company by name → company number
get_company	Profile: status, age, SIC descriptions, overdue flags
get_financials	Turnover, net assets, profit/loss, employees — parsed from iXBRL, in GBP
get_directors	Current board with appointment history across all their companies
get_psc	Persons with Significant Control, control types in plain English
get_psc_chain	Ownership traversed to ultimate beneficial owners, with termination reasons
get_compliance	ECCTA identity-verification status — who has verified, who is pending, who is overdue
get_network	Companies connected by shared directors, to depth 2

On get_compliance

The Economic Crime and Corporate Transparency Act requires every UK director and PSC to verify their identity with Companies House. Enforcement begins 18 November 2026, after which unverified officers can block filings.

The tool returns verified / pending / overdue counts plus each unverified person and their individual deadline. It deliberately distinguishes pending (deadline not yet reached — not a failure) from overdue (missed). Treating those as the same thing is the single easiest way to report a compliant company as non-compliant.

Example prompts

"Is Tesco PLC compliant with ECCTA director verification, and who still needs to verify?"

"Pull the last filed financials for 00445790 and tell me if turnover grew."

"Who ultimately owns Rolls-Royce Holdings? Trace the ownership chain."

"Which companies share directors with Barratt Developments?"

"Search for 'Monzo' and show me status, incorporation date and directors."

Plans

The anonymous endpoint needs no account at all. A free key raises the caps, and paid tiers add volume, PSC chain traversal and the ECCTA compliance endpoint.

Prices and quotas are served live from GET /v1/plans — that endpoint is the source of truth, so this README does not duplicate the numbers and cannot go stale against them. Human-readable version at registrum.co.uk.

Notes

• Company numbers are zero-padded 8-character strings: 00445790, SC000268.
• Responses are JSON, cached server-side (24h profiles/directors, 7d financials).
• The hosted endpoint is stateless and anonymous: it stores no account, and rate limiting is keyed on a hash of the calling IP rather than anything about you.
• The npm package sends User-Agent: @registrum/mcp/<version> so we can see which features developers actually use. No telemetry runs on your machine.

API reference · Issues · [e-mail]