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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false. The description goes beyond by adding operational requirements: 'Requires opensearch.predictionRankIndex', and disclaimers: 'No account access, no order placement or fund transfers. Not investment advice.' These are valuable behavioral disclosures not present in 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 a single, dense paragraph that front-loads the core purpose and then lists filters, requirements, and caveats. It is concise and structured, with no redundant filler. Every sentence adds useful operational or behavioral context.

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 has 5 optional parameters, an output schema, and annotations covering safety, the description is complete enough for an agent to call it correctly. It covers the ranking basis, filters, the required index, read-only nature, and important disclaimers. It does not explain output format, but the output schema exists and covers that.

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 covers 100% of parameters with descriptions, including defaults and allowed values. The description restates some like 'category (exact term on rank index)' and 'status (active/closed/resolved/all; default active)' but adds no new information beyond the schema. Baseline 3 is appropriate since schema handles the 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 states a clear purpose: 'Daily venue/overall ranking by volume delta (UTC rank_date)'. It identifies the resource (ranking data) and the dimension (volume delta). It is specific enough to distinguish from generic ranking tools, though it does not explicitly name alternatives among siblings like fastest_rising_ranking.

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 provides context: it is read-only research data, requires opensearch.predictionRankIndex, and involves no account access or transactions. However, it does not explicitly state when to use this tool versus alternatives, nor does it name sibling tools or exclusions. The usage is implied by 'Read-only public research data' but not directly compared.

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