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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and a closed-world scope, so safety is covered. The description adds real value beyond that by disclosing the matching behavior: the query can hit the term itself, its reading, or words appearing inside the explanation. It does not mention result counts, ranking, or pagination, which keeps it 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?

One sentence, front-loaded with the verb and resource, followed by a parenthetical of examples and then the matching rule. No filler and nothing repeated from title or annotations.

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 lookup tool with no output schema, the description conveys what is returned (Easy Japanese explanations) and how matching works. The main open question — whether the query must be Japanese script — is left unaddressed, which is the only meaningful omission.

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 0% and the single field is an unannotated string, so the description has to carry the meaning. It does so by explaining that the query may be the term, its reading, or words inside the explanation, which tells an agent what values are valid. It remains silent on whether English input is accepted, which is a residual gap.

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 verb (look up), a specific resource (Japanese administrative terms with Easy Japanese explanations), and gives concrete examples (住民票, 転入届, 保険料, 避難所) that pin down the domain. This is clearly distinguishable from get_document and list_documents, which deal with documents rather than term explanations.

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?

The intent is implied — use this when you have a term you want explained in plain Japanese — but there is no explicit statement of when to prefer it over get_document or list_documents, nor any note on prerequisites or limits. Usage is inferable rather than stated.

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