Companies House API for AI-agent research

What the official source provides

Companies House publishes the authoritative public company register for incorporated UK companies. Its official API documentation covers company search, profiles, officers, filing history and related public resources. The separate Document API serves document metadata and available filing content after a filing-history result supplies the document reference.

The source can support:

• legal name, number, status and registered-office checks;
• current and resigned officer research;
• filing-history discovery;
• Persons with Significant Control information where disclosed;
• registered charges and company-register insolvency records;
• links and references to filed documents.

The official API is the right primitive for direct Companies House access. dossaro's role is to make that evidence usable inside a repeatable agent workflow and alongside other jurisdictions.

Which Companies House API path fits the job?

The search task and the evidence task are different steps. Start with company-name search only when the company number is unknown, resolve the candidate using legal name, status and registered office, then keep the selected company number fixed for later calls.

This sequence is why Companies House API search by company name belongs to the same canonical as the filings and document workflow. Search resolves the entity; the company number anchors the evidence calls. It is not a separate keyword-variant product.

What dossaro adds

An agent can use the same dossaro primitives for a UK company that it uses for a German, Polish or French target:

• resolve the selected company and retain its entity reference;
• request profile, officer, control and document evidence;
• list relevant filings before retrieving or parsing documents;
• list registered charges or insolvency records when the assignment asks about secured debt or distress;
• preserve official links and filing metadata;
• separate no-result, unavailable and source-limited responses from confirmed negative facts;
• combine Companies House evidence with Gazette and regulatory research when the assignment requires it.

For cross-border ownership work, connect the UK result to the private-company ownership workflow.

Agent workflow

1. Start with the exact company number when known; otherwise search the legal name.
2. Compare candidate name, status, registered office and jurisdiction, then retain the selected company number.
3. Request profile, officer and PSC/control surfaces relevant to the task.
4. List filing history before selecting a document reference.
5. Fetch or parse only the document reference returned by the source.
6. List charges or insolvency rows when the assignment requires secured-debt or distress evidence.
7. Preserve dates, categories, transaction IDs and source references across every step.
8. Flag missing evidence as a review condition rather than proof of no ownership, control, security or insolvency.
9. Let the calling agent synthesize the final research answer.

The same sequence can be repeated across a target list as part of M&A target screening.

Evidence and outputs

If the assignment depends on original artifacts, use the company-register documents workflow.

Coverage and limitations

• Companies House records public disclosures; they are not a complete economic-ownership database.
• PSC information should not be treated as identical to a full cap table or final UBO conclusion.
• Empty control, officer or relationship arrays are not proof that no relevant relationship exists.
• Document retrieval and parsing depend on the filing and source path.
• A charge row documents a registered security interest; it does not reveal every facility term, lender allocation or off-register obligation.
• An empty insolvency response is not proof that no distress event exists; Gazette and other notice sources remain separate.
• UK Gazette and FCA evidence are separate source surfaces even when used in the same research assignment.
• dossaro does not replace Companies House or provide official, legal or investment advice.

Review the dossaro MCP setup guide at https://dossaro.com/agent-setup/prompt.md, configure dossaro when possible, complete OAuth with the user, then perform this task: Search for the UK target, resolve the exact Companies House company number, collect the relevant profile, officer, PSC/control, filing, charge, insolvency and document evidence, preserve every source reference, and report missing or source-limited evidence separately.