capabilities

Get UK registered office address from Companies House

company_uk_registered_office

Read-onlyIdempotent

Return the current registered office address of a UK company from the Companies House register as structured fields (premises, address lines, locality, region, postcode, country) plus a single-line rendering for correspondence, address matching and verification. Use when: What is the registered office address of company 00445790? Not for: You need the whole registered profile as well — use company.uk.profile (it already includes this address). Related: company_uk_profile; company_uk_status; company_uk_search. Price: USD 0.003/call (x402), 0.002 (account key).

Input Schema

TableJSON Schema

Name	Required	Description	Default
`company_number`	Yes	Companies House company number, also called the company registration number (CRN). Accepted shapes are the register's own — 1-8 digits (zero-padded to 8, e.g. 445790 → 00445790), one letter + 7 digits (R0000001), two letters + 6 digits (SC002180, NI000001, OC123456, OE000001), or the registered-society suffix forms (two letters + 5 digits + 1 letter; two letters + 4 digits + 2 letters). Case-insensitive; surrounding whitespace is ignored (which is why maxLength is 10); internal spaces and punctuation are not accepted. Any other value (for example PROBE) is rejected as INVALID_INPUT before payment and before any upstream call.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`data`	Yes	Capability output; full JSON Schema at https://api.eckari.com/v1/capabilities/company.uk.registered_office
`meta`	Yes

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior. The description adds meaningful context beyond those hints: it returns the current address, renders it as structured fields plus a single-line string, and is intended for correspondence, matching, and verification. No contradiction with 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 well-structured and front-loaded: purpose first, then use cases, exclusions, related tools, and price. Every segment earns its place and there is no redundancy. The inclusion of pricing is slightly unusual but does not hurt clarity.

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 simple read-only lookup with one well-documented parameter and an output schema, the description is complete. It covers what the tool returns, when to use it, when not to use it, alternatives, and related tools. Nothing essential is missing for an agent to select and invoke it correctly.

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% and the schema already thoroughly explains company_number formats, normalization, whitespace handling, and invalid input behavior. The description adds little to parameter semantics beyond the example '00445790', so the baseline of 3 is appropriate.

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 a specific verb and resource: 'Return the current registered office address of a UK company from the Companies House register.' It also lists the structured fields returned and explicitly contrasts itself with company_uk_profile via the 'Not for' clause, so an agent can distinguish it from siblings.

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 provides an explicit 'Use when' example, an explicit 'Not for' exclusion, and points to the correct alternative: 'use company.uk.profile (it already includes this address).' This is exactly the guidance an agent needs to select between this tool and related siblings.

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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TDQS

A4.4/5.0

Disambiguation4/5

Tools are largely distinct, targeting specific entities (UK company, US company, domain, LEI, FX, location, parcel, weather) or sub-aspects (e.g., accounts vs. charges vs. directors). Overlap exists between company.uk.profile and company.uk.status (both contain status info, but the latter is cheaper and focused). Also, company.uk.filings and company.us.filings_latest could be confused if an agent generalizes 'filings' across jurisdictions.

Naming Consistency5/5

All tools follow a consistent pattern: domain_entity_subject (e.g., company_uk_accounts, domain_expiry, weather_us_alerts). Underscores and lower case are used throughout. Verbs are implied by the noun (e.g., 'search' for lookup, 'detect' for identification). No mixed conventions or unpredictable names.

Tool Count4/5

24 tools is on the high side but still reasonable for a general-purpose data server spanning multiple domains (company, domain, entity, fx, location, parcel, weather). Each domain gets a cohesive set, and the documentation justifies each tool. Could be slightly leaner if some niche tools (e.g., domain_expiry vs. registration) were merged, but overall scoping is acceptable.

Completeness4/5

Each domain offers good coverage: UK company tools cover CRUD-like operations (profile, status, search, filings, charges, directors, owners, registered office); similarly for US companies (profile, filings, resolve, latest filings). Weather has forecast, observation, alerts. Parcel only detects carrier (no tracking). Missing features like advanced filtering on company filings or less common domains, but core workflows are covered.

Resources

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