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 real value by spelling out the full returned field set (location, segment, equipment, book values breakdown, headcount) and their units (yen, area). It does not mention pagination, historical depth limits, or what happens when a company reports no overseas subsidiaries.

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 core enumeration is front-loaded and efficient, but every clause is duplicated verbatim in Japanese, roughly doubling length beyond what an English-reading agent needs. The trailing ISO 8601 / JST conversion boilerplate appears to be generic template text with little relevance to a book-value and headcount dataset.

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, the description correctly compensates by enumerating the return columns and their units, which is the main thing an agent needs to decide whether to call it. Missing are caveats on history depth and coverage gaps for companies that omit the facilities section.

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%, including the YYYY-MM pattern and the omit-for-latest default, so the schema carries the parameter burden. The description only reinforces the source document (annual securities report), which implicitly motivates fiscalPeriod but adds no new syntax or edge-case guidance.

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 opens with a framing question and then names the exact resource (major facilities from the annual securities report) and its granularity (one row per site), then enumerates the columns returned. This lets an agent distinguish it from near-neighbours like get_subsidiaries, get_segments and get_workforce without opening the 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?

Usage is only implied by the rhetorical question 'Where does the company operate?' and by the mention of the annual securities report as the source. There is no explicit when-to-use statement, no exclusion naming a sibling (e.g. use get_segments for segment financials), and no note about how far back fiscalPeriod can go.

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