detect_price_change

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

Annotations already indicate read-only, idempotent, non-destructive behavior. The description adds valuable context: cache-only (no API call), supported plans (Free/Light/Standard/Premium), and data availability timing. No contradictions with 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 concise (3 sentences plus bullet lists) and front-loaded with the core purpose. Every sentence adds value: purpose, alternative, timing, plans, parameter format. No redundant or vague phrasing.

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 one simple parameter, clear annotations, and an existing output schema, the description covers all necessary context: purpose, usage boundaries, behavior, parameter format, data availability, and plan support. Nothing missing for effective use.

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?

Only one parameter (date) with 0% schema description coverage. The description provides the date format (YYYY-MM-DD or YYYYMMDD), compensating for the schema gap. Lacks details like validation or range, but sufficient given single param.

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 returns a daily advance/decline summary for all listed equities, with Japanese terms. It specifies the exact use case ('値上がり銘柄数・値下がり銘柄数・騰落集計 queries') and explicitly distinguishes from sibling tools $get_advance_decline_ratio$ and $get_sector_performance$.

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 (advance/decline queries) and when not (rolling ADR ratio, sector breakdown) with named alternatives. It also notes data availability time (~17:15 JST), providing complete usage guidance.

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