Search HMRC Guidance

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the description only needs to add context. It adds the return values (titles, URLs, summaries, last-updated dates) and specifies the source (official GOV.UK content API), which goes beyond the annotations. It does not mention rate limits or authentication, but for a read-only search this is adequate.

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 four sentences long, front-loaded with the usage directive, and contains no fluff. Each sentence serves a distinct purpose: when to use, what it returns, where it searches, and why it's authoritative. It is exceptionally concise and well structured.

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?

With an output schema present and only two parameters (one required), the description provides sufficient context: the purpose, the data source, the return fields, and a warning about alternatives. It is fully adequate for an agent to select and invoke the tool 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?

Schema coverage is 100% with detailed descriptions for both query and limit parameters. The description does not add any parameter-specific semantics beyond what the schema already provides. Baseline 3 is appropriate because the schema carries the full burden.

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 identifies the tool's function: searching GOV.UK for HMRC tax guidance. It specifies the verb 'search', the resource 'HMRC tax guidance', and the scope (GOV.UK content API filtered to HMRC publications), distinguishing it from sibling tools like gov_govuk_search and other HMRC-specific tools.

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 says 'USE THIS TOOL WHEN searching GOV.UK for HMRC tax guidance' and warns against web search with 'do not supplement', providing clear when-not guidance. However, it does not name sibling tools as explicit alternatives, so it falls just short of a perfect 5.

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