companies-house-screening-mcp

Get persons with significant control

get_psc

Read-onlyIdempotent

Identify who owns or controls a UK company: returns persons with significant control, including shareholding bands, voting rights, director appointment rights, and current or ceased interests.

Instructions

Who OWNS a company. Use this for any question about ownership, shareholders, beneficial owners or who is ultimately behind a business — the company profile does not carry ownership and get_company will not answer it. Returns each person or entity with significant control: how much they own (shareholding band), how that control is held (voting rights, right to appoint directors), and whether the interest is current or ceased. Ownership is often not the same as the directors, so this is a different question from get_officers. Where a company cannot identify a controller it files a statement instead of a person, and that statement is returned in the name field. Needs a company number.

Input Schema

TableJSON Schema

Name	Required	Description
`verbose`	No	Also return the untouched Companies House payload under `raw`, alongside the shaped result. Roughly two and a half times the size; use it only when a field you need is missing from the shaped result.
`start_index`	No	Zero-based offset into the full result set. Use pagination.has_more to decide.
`company_number`	Yes	Eight-character Companies House number, such as 00000006 or SC123456. Leading zeros may be omitted. This tool does not accept a company name — call find_company first if that is all you have.
`items_per_page`	No	How many records to return. Defaults to the API default; the maximum is 100.

Output Schema

TableJSON Schema

Name	Required	Description
`raw`	No	The untouched Companies House payload. Present only when verbose was true.
`meta`	Yes	Provenance and budget for this answer.
`pagination`	Yes	Where this page sits in the full result set.
`controllers`	Yes
`active_count`	No
`ceased_count`	No
`company_number`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.4.0Sep 5, 2026

changedOutput schema / properties / meta / properties / licence / description

Previous value: -"Companies House data is Open Government Licence v3.0."New value: +"OGL v3.0 applies to eligible public-sector information. Personal data and other OGL exclusions are not licensed by this label; applicable data-protection duties still apply."

First observedv0.2.0Aug 30, 2026

TDQS

A4.7/5.0

Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavior beyond the annotations: it explains the returned fields, states that interests can be current or ceased, and discloses the edge case where a statement is returned in the name field instead of a person. This provides actionable behavioral context without contradicting the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is dense but every sentence earns its place: it states the core purpose, gives usage context, distinguishes from siblings, explains the return data, and covers a key edge case. The most important routing signal is front-loaded with 'Who OWNS a company,' and the final 'Needs a company number' is a useful practical requirement. There is no filler or repetition.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only, idempotent tool with an output schema and 100% schema parameter coverage, the description is complete. It explains what the tool returns, when to use it, how it differs from related tools, how to handle the statement fallback, and the prerequisite of a company number. Pagination is already covered by the schema's start_index and items_per_page descriptions, so no further behavioral detail is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the input schema already documents all four parameters thoroughly, including company_number format, verbose behavior, pagination offset, and items_per_page. The description adds only 'Needs a company number' and the hint to call find_company if only a name is available, which the schema already states. This is the baseline 3 case: the schema carries the parameter-semantics burden and the description does not need to compensate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with the concrete, memorable phrase 'Who OWNS a company' and immediately identifies the resource: persons with significant control, including shareholding bands and control mechanisms. It also differentiates itself from related tools by explicitly stating that get_company will not answer ownership questions and that ownership is a different question from get_officers, so an agent can distinguish it from siblings without opening schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives explicit when-to-use guidance: 'Use this for any question about ownership, shareholders, beneficial owners or who is ultimately behind a business.' It also names exclusions and alternatives, warning that get_company will not answer this and directing users to find_company if they only have a company name. This is exactly the kind of routing context an agent needs.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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