detect_price_change

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

Annotations declare readOnlyHint, destructiveHint, idempotentHint, and openWorldHint, but the description adds that it is cache-only (no API call) and data is available ~17:15 JST on trading days. This extra context is valuable, though it could mention that the output is a summary (counts) rather than a list. Still, it goes beyond what annotations provide.

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 with five sentences, each adding distinct value: main purpose, usage context, data availability, plan support, and parameter format. It is front-loaded and contains no filler.

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's simplicity (one parameter, output schema exists), the description covers all necessary aspects: what it returns, when to use alternatives, data freshness, and plan restrictions. It is complete for an agent to correctly select and invoke the tool.

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 has one parameter 'date' with no description (0% coverage). The description fully compensates by specifying the format: 'Trading date (YYYY-MM-DD or YYYYMMDD).' This adds critical meaning beyond the schema.

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 the daily advance/decline summary (number of rising vs falling stocks) for all listed equities. It distinguishes itself from siblings like get_advance_decline_ratio (rolling ADR ratio) and get_sector_performance (sector breakdown). The name may be slightly misleading, but the description compensates effectively.

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 explicitly states when to use this tool (for advance/decline queries) and provides specific alternatives: 'For rolling ADR ratio use get_advance_decline_ratio; for sector breakdown use get_sector_performance.' It also notes the data availability time and that all plans are supported.

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