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

Annotations only declare readOnlyHint=true; the description supplies the substantive behavior: PER uses latest annual EPS, PBR uses latest reported BPS including quarterly, priceDate is the price date used, annual dividend includes company forecast when available, and ratios are 0-1 decimals. It also explains the 'N or more' output when progressiveDividendYearsCapped is true, which is non-obvious return-value behavior.

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 metric list and the sibling routing are front-loaded and earn their place, but the description is bloated by a full Japanese restatement of the same content plus a duplicated bilingual date-format note. For an agent consumer the second language block and the repeated ISO 8601 explanation are largely redundant text.

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-parameter read-only tool with no output schema, the definition covers computation basis, unit conventions, forecast handling, and date encoding — everything needed to interpret the returned numbers correctly. Nothing material 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?

Schema coverage is 100% for the single `symbol` parameter, with an example ("7203" = Toyota) already in the schema, so the description adds nothing about the parameter. Baseline 3 applies when the schema fully carries parameter meaning.

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 resource (latest valuation and growth metrics computed with the latest close) and enumerates the exact fields returned: PER, PBR, dividend yield, annual dividend, consecutive non-decrease years, and 3y/5y CAGR of dividend/revenue/net income/EPS. It also distinguishes itself from the two nearest siblings, get_key_metrics (per-period) and get_quote (price/changes).

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?

Explicitly routes the agent: 'For per-period values use get_key_metrics; for price and changes use get_quote.' The selection condition is stated, not implied, so an agent can choose among the three metric/price tools without opening schemas.

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