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

Annotations already declare read-only, idempotent, and non-destructive behavior, so the description only needs to add scope. It does so by specifying that output is fact-only, based on public master-table facts, and excludes unsupported superiority claims, which prevents an agent from expecting subjective or recommendation-style output.

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?

Exactly two sentences, with the core function in the first and a boundary condition in the second. No wasted words.

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?

For a one-optional-parameter, read-only comparison tool with an output schema and full annotation coverage, the description provides a complete mental model: what it returns, its factual basis, and its limitations. Nothing essential 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 only parameter, competitor, is fully described in the schema with an enum of supported slugs, so schema coverage is 100%. The description references 'supported blood-testing service' but does not add semantics beyond the schema; baseline 3 is appropriate.

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?

States a specific verb ('Returns'), a clear object ('side-by-side comparison of Vitals Vault and a supported blood-testing service'), and the evidential basis ('public master-table facts and methodology'). This clearly distinguishes it from sibling read tools that retrieve biomarkers or lab packages.

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 implies the tool is for factual comparisons rather than recommendations or medical advice, and its 'excludes medical advice' line hints at a limitation. However, it does not explicitly compare against siblings such as recommend_panel or search_lab_catalog, nor state when not to use it beyond avoiding medical-advice requests.

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