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

Beyond the annotations (readOnlyHint=false, openWorldHint=true, destructiveHint=false), the description discloses deterministic keyword matching, that the text is never paraphrased or summarised, the $0.01 USDC cost via x402, the 402-challenge flow described in the parameter schema, and that non-matching queries return a 400+ decline with no charge. This is substantial behavioral context well beyond what annotations carry.

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 front-loaded with the core purpose, then gives efficient sibling routing, cost, and caveats. It is longer than the minimum but each sentence contributes (corpus statistic, 'never paraphrased', payment details). A small redundancy exists between 'as written' and 'Never paraphrased', but this does not materially dilute it.

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 no output schema, the description fully covers what the tool returns: the exact passage with references and disclaimer, a 400+ decline when nothing matches, and a 402 challenge when payment proof is missing. It also explains cost, author qualifications, and intended content domain. For a 2-param tool with a straightforward pass-through, nothing an agent needs to invoke it correctly is missing.

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 input schema already provides 100% coverage of both parameters: query's deterministic matching and phrasing guidance, and paymentHeader's optional payment proof with the 402-challenge behavior. The tool description adds no parameter-specific meaning beyond what the schema already states, so the baseline of 3 applies.

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 states a specific action (retrieve the one passage that best matches the question), the resource (Sarah Anderson's passage with references and disclaimer), and distinguishes it from clinic_clinical_answer (shortest matching unit) and clinic_clinical_section (article body). It is unambiguous and names the sibling variants, so an agent can tell them apart.

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?

It gives explicit routing rules: use clinic_clinical_answer when the shortest matching unit suffices, and clinic_clinical_section when the full article body is needed. It also provides a data point (65 of 76 headings identical across rungs) that supports deferring to the cheaper sibling, making the when-to-use decision concrete.

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