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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds useful behavioral detail that the fields are static reference data with prices quoted in yen including tax, which prevents currency/tax misinterpretation, but it says nothing about staleness, caching, or whether values are guaranteed current.

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?

A single compact sentence listing the covered topics, front-loaded with the primary subject (what the service translates). It is efficient, though the comma-separated enumeration is dense and could be split so the highest-value facts (prices, limits) lead.

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 zero-parameter read-only reference tool with no output schema, the description carries the return-value burden and does so by enumerating the returned subject areas. It is nearly complete, with only minor gaps around whether the information is versioned or region-specific.

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?

The tool takes zero parameters, so the baseline is 4. The description correctly spends its words on what is returned rather than on nonexistent inputs, which is the right allocation for a parameterless tool.

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 enumerates the exact content the tool returns (translation coverage, accepted files, limits, prices, delivery times, ordering/payment flow), which effectively defines the resource and separates it from siblings like create_order or quote_document. It lacks an explicit verb ('returns'/'describes'), so it reads as a content list rather than a stated action.

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?

There is no explicit when-to-use statement and no named alternatives, but the enumerated content implies the use case: consult this before ordering or quoting for pricing, limits and file requirements. The agent must infer that this is the entry-point/reference tool rather than being told.

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