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

Annotations already establish readOnly, idempotent, non-destructive, and closed-world behavior, so the bar is lower, and the description still adds real value: unknown words come back as found:false with ipa null and nothing is generated or guessed. That guarantees determinism beyond what the annotations say, though lookup/pagination mechanics go unmentioned.

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?

Front-loaded with the core action and sized in two short sentences, with the fallback behavior appended where it is most useful. The bilingual Korean sentence restates the same content, which is redundant for an English-reading agent but not wasteful enough to hurt.

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 rightly carries the return-value burden and does explain the found:false/ipa null outcome. Nothing critical is missing for calling the tool correctly; only richer detail on the found-word response shape could improve it.

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%, so the description must compensate, and it partly does: 'up to 20 words' explains the words param and 'one language' explains lang. It does not mention that lang defaults to en_US or that 29 enum values exist, leaving an agent reliant on the schema to discover accepted language codes.

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 (look up) and resource (IPA pronunciation) with scope: up to 20 words, one language, from WIHP's dictionary. It is clearly distinguishable in spirit from the siblings, but it never names list_supported_languages or to_hangul to rule out confusion, so sibling differentiation is only implicit.

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 batch limit of 20 words and the single-language constraint imply the intended use case, and the found:false note tells the agent what to expect for missing entries. However, there is no explicit statement of when to prefer this tool over siblings such as to_hangul or list_supported_languages.

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