Get VAT Rate for Commodity

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

The description discloses that the tool 'Uses a static lookup table current as of 22 Nov 2023 (Autumn Statement)' and notes that rates may have changed. This goes beyond annotations (readOnlyHint=true, idempotentHint=true) by explaining the data source and freshness. No contradictions 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.

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

The description is extremely concise: three short sentences plus a bolded usage note. Every sentence provides essential information without redundancy. It is front-loaded with the usage directive.

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

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

Given the tool's simplicity (one parameter, read-only, output schema present), the description covers purpose, usage guidelines, data limitations, and fallback tool. It is complete and provides all necessary context for an agent to use it correctly.

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

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

The parameter schema already provides a description ('Commodity code or plain-English description'). The tool description adds examples ('E.g. 'food', 'domestic fuel'', 'software'). This adds value beyond the schema, but does not specify format constraints or validation details, so it's above baseline but not perfect.

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

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

The description explicitly states 'USE THIS TOOL WHEN you have a UK commodity or service description and want its VAT rate category.' It clearly identifies the verb (get) and resource (VAT rate for commodity), and distinguishes from the sibling hmrc_search_guidance by noting it as a fallback for time-sensitive advice.

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

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

The description gives explicit usage context: when you have a UK commodity/service and want its VAT rate. It also provides an important when-not-to-use guideline for time-sensitive advice, directing to hmrc_search_guidance. It mentions data currency limitations, helping the agent decide when to trust the result.

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