Search HMRC Guidance

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

Annotations already declare readOnlyHint, destructiveHint, idempotentHint, and openWorldHint. The description adds that it searches the official GOV.UK content API filtered to HMRC publications, and returns specific fields (titles, URLs, summaries, dates). This provides useful behavioral context beyond annotations, though rate limits or pagination are not mentioned.

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 concise (4 sentences) and front-loaded with the key instruction. Every sentence adds value: purpose, output, source, and authority.

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 simple search nature, complete annotations, and presence of an output schema, the description covers all necessary context: what it searches, what it returns, and its authoritativeness.

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?

Schema coverage is 100%, so baseline is 3. The description does not add new parameter semantics; it repeats the output format but not parameter details. The schema already explains 'query' and 'limit' adequately.

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 clearly states the tool's purpose: searching GOV.UK for HMRC tax guidance. It specifies the verb 'search', the resource 'GOV.UK HMRC tax guidance', and the scope (VAT, income tax, etc.). It implicitly distinguishes from siblings by noting that web search returns outdated info.

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 explicitly states when to use the tool ('USE THIS TOOL WHEN searching GOV.UK for HMRC tax guidance') and provides a negative guideline ('Web search returns out-of-date or third-party reproductions — do not supplement'), giving clear context and alternatives.

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