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

Annotations already establish readOnlyHint=true, so the safety profile is covered. The description adds material context the annotations do not: that change values are decimal fractions (0.03 = 3%), that timestamps are ISO 8601 UTC with a stated +9h offset for Japan time, and which fields are deliberately excluded. It stops short of describing freshness or what happens when the market is closed, which would be useful for a 'latest' snapshot.

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 English content is well front-loaded and each fact earns its place, but the entire description is immediately restated in Japanese, roughly doubling length with no new information. The bilingual duplication is defensible for audience coverage yet inefficient for an agent parsing the definition.

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 no output schema and one simple required parameter, the description covers return fields, units, date formats, and sibling exclusions – enough to call the tool correctly. Missing details about data freshness or null/empty handling for a 'latest' snapshot keep it from being fully complete.

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 description coverage is 100% and the single symbol parameter is already documented with a concrete example ('7203' = Toyota). The description adds no syntax, format, or validation details for the parameter, so the baseline of 3 applies.

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 verb and resource ('Latest price snapshot') and enumerates exactly which fields are returned (close price, price date, change windows, market cap). It also names the sibling tool (get_key_metrics_latest) that holds the metrics this tool does not return, so an agent can distinguish the two without opening either schema.

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 away from this tool for PER, PBR, dividend yield, streak years, and CAGRs, pointing to get_key_metrics_latest. It does not address other plausible alternatives such as get_batch_quotes for multiple tickers or get_historical_prices for time series, so the routing guidance is clear but not exhaustive.

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