get_advance_decline_ratio

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

Annotations already declare readOnlyHint and idempotentHint, so the agent knows it's safe. The description adds valuable context: cache-only behavior and plan support details ('no API call'). This adds beyond 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 well-structured: purpose first, then usage, thresholds, sibling differentiation, plan info, and params. It's not overly verbose for the information conveyed, though the Japanese terms add a bit of length.

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 and the presence of an output schema, the description covers all key aspects: purpose, usage context, thresholds, parameter details, and plan support. It does not describe the output schema, but that is acceptable since the schema exists.

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 has 0% description coverage, but the description documents both parameters: date format (YYYY-MM-DD or YYYYMMDD) and period as trailing trading days with default 25. This adds meaning beyond the bare schema, though format details could be more precise.

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 it returns the advance/decline ratio over the last period trading days. It explicitly distinguishes from detect_price_change (daily counts) and get_sector_performance (sector breakdown), making the tool's unique purpose unambiguous.

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 explicit when-to-use guidance (for 'market heat' queries) and threshold conventions (>120 overbought, <70 oversold). It also names specific alternative tools for related needs, offering clear decision support.

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