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

Annotations already declare readOnlyHint=true, so the safety profile is covered; the description adds genuinely useful context beyond that: units (yen), that both current and prior year are returned, that non-audit share is a 0–1 ratio, and the exact date/time conventions. It does not discuss coverage gaps (e.g. companies that disclose nothing) or response shape, so it stops short of a 5.

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?

It is front-loaded, with the purpose and field inventory stated before the format notes, which is good. However, the fully duplicated Japanese rendering of both the content list and the date-format rules roughly doubles length without adding information for a single reader, and the timezone note is repeated in both languages.

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?

There is no output schema, so the description carries the burden of describing the return values, and it does so thoroughly (fee categories, entities, periods, network firms, ratio, currency). Only minor gaps remain, such as whether a single object or a time series is returned when fiscalPeriod is omitted.

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%, so the baseline is 3: symbol and fiscalPeriod are already fully documented in the schema, including the YYYY-MM pattern and the omit-for-latest behavior. The description's date-format paragraph concerns returned values rather than the parameters, so it adds no new 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?

The description names a specific resource and scope: fees paid to the independent auditor per the annual securities report, broken into audit-service and non-audit-service fees, reporting company / consolidated subsidiaries / total, current and prior year, plus network-firm fees and the non-audit share. That is far more specific than any sibling (get_director_compensation, get_sga_breakdown), so an agent can identify it on sight.

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?

Usage is only implied by the subject matter; there is no explicit when-to-use, when-not-to-use, or named alternative among the many sibling tools. The only real guidance is the format note (ISO 8601 UTC, add 9 hours for JST) and the schema's note that omitting fiscalPeriod returns the latest annual report.

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