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UK Business Tools - Ledgerhall

by dev.fly.uk-business-mcp

Validate UK VAT Number (HMRC)

dd_vat_validate
Read-onlyIdempotent

Validate a UK (GB) VAT number against the HMRC register. UK numbers only.

Returns the trading name and address as registered with HMRC for VAT purposes. The VAT-registered trading address often differs from the Companies House registered address — that discrepancy is a due diligence signal worth noting.

Non-UK (EU) VAT numbers cannot be validated here — use the EU VIES service for other member states.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
vat_numberYesUK (GB) VAT registration number — this tool validates UK numbers only. Accepts: 'GB123456789', '123456789', 'GB 123 456 789'. GB prefix and spaces normalised automatically.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
validYesTrue if HMRC confirmed the VAT number is currently registered. False means HMRC returned 404 (not registered / deregistered).
vat_numberYesCanonical VAT number in 'GB<9 digits>' format.
trading_nameNoTrading name registered with HMRC for VAT. Compare with the Companies House name — discrepancies are a due diligence signal.
registered_addressNoVAT-registered trading address. May differ from the Companies House registered office address.
consultation_numberNoHMRC consultation reference number for this lookup.

TDQS

A4.5/5.0
Behavior4/5

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

Beyond annotations (readOnly, idempotent, non-destructive), the description discloses the return payload (trading name and address) and adds the notable behavioral trait that the trading address often differs from Companies House. It does not mention rate limits or error handling, but the core behavior is transparent.

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?

Three concise paragraphs: purpose, return value with due diligence note, and exclusion with alternative. Every sentence contributes meaning, no redundancy.

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 single-parameter read-only lookup tool with an output schema, the description covers scope, return content, and alternatives. It lacks nothing essential 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%, so the parameter is fully documented in the schema (formats, normalization, UK-only). The main description adds minimal param-specific detail beyond repeating 'UK numbers only.' The baseline of 3 applies since the schema carries the full burden.

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+resource: 'Validate a UK (GB) VAT number against the HMRC register.' It clearly distinguishes from sibling tools by specifying UK-only scope and the HMRC register, which is different from company search or VAT rate tools.

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?

Explicit guidance is given: 'Non-UK (EU) VAT numbers cannot be validated here — use the EU VIES service for other member states.' It also provides contextual value by explaining the due diligence signal of address discrepancies, which implies when this tool is appropriate.

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

All UK Business Tools - Ledgerhall toolsInspect
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TDQS

A4/5.0
Disambiguation4/5

Tools are well-grouped by domain prefixes (dd_, gov_, law_, prop_) with clear descriptions that differentiate them. However, there is minor overlap, e.g., dd_search could be used instead of individual searches, and dd_fetch versus dedicated profile tools might cause confusion.

Naming Consistency5/5

All tools follow a consistent verb_noun pattern with domain-specific prefixes (dd_, gov_, law_, prop_). Names are descriptive and predictable, e.g., dd_charity_search, gov_govuk_search, law_bills_search_bills.

Tool Count4/5

70 tools is high but justified by the broad scope covering due diligence, government, legal, and property domains. Each domain has a reasonable number of tools (about 15-20 each). The count is on the upper end but still manageable.

Completeness5/5

The tool set is comprehensive across all domains: full CRUD for companies and charities, detailed legal research (cases, legislation, parliament, citations), property data (EPC, planning, price paid, rentals), and government information. No obvious gaps for the intended use cases.

Resources