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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds substantive scope disclosure beyond that—components, containing characters, confusable look-alikes, sound-component family, and words—which tells the agent what the call actually yields. It stops short of noting any limits on result size or ordering.

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 purpose, then the returned relation types, then usage. Three sentences, each carrying distinct information, with no filler or repetition 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?

There is no output schema, so the description properly carries the burden of describing what is returned, and it does so thoroughly. Combined with a fully documented single parameter and benign read-only annotations, an agent has everything needed to select and invoke this correctly.

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 coverage is 100% and the single parameter is already documented as 'Exactly one Chinese character', so the baseline is 3. The description earns an extra point by restating the boundary in operational terms ('Do not use it for words of two or more characters'), which disambiguates the maxLength=4 input against multi-character word lookups.

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?

Opens with a specific verb and resource ('Show how one Chinese character connects to others') and then enumerates the exact relation types returned. It is clearly distinguishable from siblings like lookup_word, search_dictionary, and get_topic_words, which serve different retrieval goals.

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 three concrete use cases (learn a character through its parts, disambiguate look-alikes, explore a character family) and an explicit exclusion ('Do not use it for words of two or more characters'). Nothing about when to pick this over a lookup tool 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.