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

Annotations already declare readOnly/openWorld=false/destructive=false, so safety is covered, and the description goes further by disclosing the result cap ('up to 10 matching words') and the per-result fields (pinyin, meaning, HSK level, link). No output schema exists, so this return-shape detail is genuinely load-bearing; only pagination/ordering behavior remains unspecified.

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?

Three sentences, all earning their place: purpose/inputs first, return shape second, routing exclusions last. No filler, no restatement of the title.

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 single-param read-only lookup with no output schema, the description supplies everything an agent needs: query forms, result cap, result fields, and routing against siblings. Nothing material is missing.

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?

There is a single required parameter and schema description coverage is 100%, so the schema already documents the accepted input forms. The description restates the same character/pinyin/English acceptance without adding format or syntax detail beyond the schema, matching the baseline 3 for a fully documented param.

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 (search) and resource (a Mandarin Chinese dictionary) and enumerates the accepted query types. It also names the scope limit (headwords, not sentences), which lets an agent distinguish it from segment_text and search_grammar without opening any 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?

Gives explicit when-to-use ('user wants the Chinese for an English word, or does not know the exact headword') and when-not-to-use ('whole sentences (use segment_text) or grammar questions'), each with a named alternative. Nothing about selection is left to inference.

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