Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/sophymarine/openregistrynpx agentmods add skills/sophymarine/openregistry/uk-companies-houseWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/sophymarine/openregistry/uk-companies-house)<a href="https://agentmods.dev/skills/sophymarine/openregistry/uk-companies-house"><img src="https://agentmods.dev/badge/skills/sophymarine/openregistry/uk-companies-house/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/sophymarine/openregistry/uk-companies-house"><img src="https://agentmods.dev/badge/skills/sophymarine/openregistry/uk-companies-house.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00000 | $0.00911 |
| Opus 5 | $0.00000 | $0.00456 |
| Sonnet 5 | $0.00000 | $0.00182 |
| Haiku 4.5 | $0.00000 | $0.00091 |
Grade A, and why
United Kingdom — Companies House Lookup scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 73 lines — stays where its author put it; the contents beside it link to each section on GitHub.
United Kingdom — Companies House Lookup
Live, direct-to-government access to Companies House (UK Department for Business and Trade).
Single-country variant of the cross-border Cross-Border UBO Chain Walker. Use this skill when the user is explicitly focused on United Kingdom.
What you get
- Direct query to Companies House. Every tool call hits Companies House (UK Department for Business and Trade) at the moment you ask. No nightly scrape, no aggregator middle layer.
- Unmodified responses. Field names, status codes, and (where available) raw filing bytes are returned exactly as the registry's own system emits them.
- Native ID format support. 8-character alphanumeric (e.g.
00445790for Tesco PLC,08804411for Revolut Ltd). - Sample entity: Revolut Ltd.
Available tools (jurisdiction = GB)
search_companies, get_company_profile, get_officers, get_persons_with_significant_control, get_charges, list_filings, get_financials, fetch_document, search_officers, get_officer_appointments
For every tool, pass jurisdiction: "GB" (case-insensitive).
Example prompts
Walk Revolut Ltd's PSC chain across borders
Pull all current directors of Tesco PLC (00445790)
List the latest 5 filings for AstraZeneca PLC and download the most recent annual report
Workflow
Step 1 — Resolve the entity
search_companies({ jurisdiction: "GB", query: "<name or ID>" })
get_company_profile({ jurisdiction: "GB", company_id: "<id>" })
Step 2 — Pull the relevant register slice
Pick from the available tools list above. For UBO walks across borders, return to the Cross-Border UBO Chain Walker.
Quirks specific to United Kingdom
- PSC Register data is publicly accessible — no AML gating in the UK.
nature_of_controlstrings are stable enums (e.g.ownership-of-shares-75-to-100-percent,voting-rights-25-to-50-percent) — useful for downstream pipelines.- Companies House preserves both legacy and current name spellings; we return verbatim.
- FC-prefixed numbers indicate UK branches of overseas companies — they typically don't file local accounts.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 12d ago First seen · 73 lines · 0 tokens per session scan A 782bd6357c63
United Kingdom — Companies House Lookup is a skill published in the GitHub repository sophymarine/openregistry (18 stars, last pushed 5d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 911 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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