Companies House

Get Persons With Significant Control

get_persons_with_significant_control

Read-onlyIdempotent

Retrieve PSC (beneficial owner) records for a UK company by company_number (from search_companies). Returns each PSC's name, kind (individual-person / corporate-entity / legal-person), natures of control (e.g. ownership-of-shares-75-to-100-percent), country of residence, nationality, notification date, and ceased date.

Input Schema

TableJSON Schema

Name	Required	Description
`start_index`	No	Pagination offset (default 0)
`company_number`	Yes	UK company number (e.g. "07098618") OR the company NAME (e.g. "Ocado Group") — a name is resolved here automatically and the match is echoed back as resolved_from_name. Pass whichever you have; do not guess a number from memory, since a plausible wrong one returns a clean empty result that reads as "nothing filed" for a company that may not exist.
`items_per_page`	No	1-100 (default 25)

Output Schema

TableJSON Schema

Name	Required	Description
`total`	Yes	Total number of persons with significant control
`persons`	Yes	List of beneficial owners with significant control
`company_number`	Yes	UK company number
`resolved_from_name`	No	Present only when a NAME was passed instead of a number. Shows which company answered, so a caller can see the resolution rather than assume it.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedAug 14, 2026

changedInput schema / properties / company_number / description

Previous value: -"UK company number"New value: +"UK company number (e.g. \"07098618\") OR the company NAME (e.g. \"Ocado Group\") — a name is resolved here automatically and the match is echoed back as resolved_from_name. Pass whichever you have; do not guess a number from memory, since a plausible wrong one returns a clean empty result that reads as \"nothing filed\" for a company that may not exist."

addedOutput schema / properties / resolved_from_name

Added value: +{
+  "description": "Present only when a NAME was passed instead of a number. Shows which company answered, so a caller can see the resolution rather than assume it.",
+  "properties": {
+    "company_name": {
+      "description": "Official name of the matched company.",
+      "type": "string"
+    },
+    "company_number": {
+      "description": "The number it resolved to.",
+      "type": "string"
+    },
+    "resolved_from": {
+      "description": "The name the caller passed.",
+      "type": "string"
+    },
+    "status": {
+      "description": "Company status; an active match is preferred over a dissolved namesake.",
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

Changed2 schema fields changedMay 22, 2026

addedInput schema / examples

Added value: +[
+  {
+    "company_number": "00006245"
+  }
+]

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "company_number": {
+      "description": "UK company number",
+      "type": "string"
+    },
+    "persons": {
+      "description": "List of beneficial owners with significant control",
+      "items": {
+        "properties": {
+          "address": {
+            "description": "Address details of PSC",
+            "type": [
+              "object",
+              "null"
+            ]
+          },
+          "ceased_on": {
+            "description": "Date PSC ceased (ISO format) if applicable",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "country_of_residence": {
+            "description": "Country of residence",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "identification": {
+            "description": "Identification details",
+            "type": [
+              "object",
+              "null"
+            ]
+          },
+          "kind": {
+            "description": "Kind of person (individual, corporate-entity, etc.)",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "name": {
+            "description": "Name of person or entity with significant control",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "nationality": {
+            "description": "Nationality",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "natures_of_control": {
+            "description": "Nature(s) of control exercised",
+            "items": {
+              "type": "string"
+            },
+            "type": "array"
+          },
+          "notified_on": {
+            "description": "Date PSC entry was notified (ISO format)",
+            "type": [
+              "string",
+              "null"
+            ]
+          }
+        },
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "total": {
+      "description": "Total number of persons with significant control",
+      "type": "number"
+    }
+  },
+  "required": [
+    "company_number",
+    "total",
+    "persons"
+  ],
+  "type": "object"
+}

First observedMay 11, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Annotations already declare the operation read-only, idempotent, and non-destructive. The description adds value by detailing what data is returned (name, kind, natures of control, etc.), which goes beyond the annotations and helps the agent anticipate the response. It does not mention pagination behavior, but that is covered by the schema parameters.

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 two clear sentences with no fluff. The first sentence states the core action and input; the second lists the returned fields. Each sentence earns its place and provides high-value information in a compact form.

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

Completeness4/5

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

Given the tool's moderate complexity (3 params, output schema present, strong annotations), the description is adequately complete. It explains the purpose, the input source, and the return fields. It does not elaborate on pagination or name resolution, but the schema covers those details, so the description does not need to repeat them.

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 schema already fully documents all three parameters. The description adds minimal parameter-related context: it mentions company_number comes from search_companies. It also slightly misleads by saying 'by company_number' while the schema notes the parameter can also accept a company name, but since the schema is explicit, the impact is limited.

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 starts with a specific verb 'Retrieve' and clearly identifies the resource: 'PSC (beneficial owner) records for a UK company'. It also lists the key input (company_number) and differentiates from sibling tools like get_officers or get_company by focusing on PSC/beneficial owner records.

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

Usage Guidelines4/5

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

It provides clear context for when to use this tool: when you need PSC/beneficial owner records for a UK company. It also hints at a prerequisite by saying 'by company_number (from search_companies)', implying you should first use search_companies to obtain a valid company_number. However, it does not explicitly name alternative tools or state when not to use it.

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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