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

Annotations already establish readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds the return contents (Chinese name, pinyin, element associations, core attributes, symbolic meaning), which provides some behavioral context, but it does not go beyond that to mention error behavior, case sensitivity, or response shape.

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?

The description is three sentences of purposeful, front-loaded text. The primary lookup behavior is stated first, followed by return contents and a clear usage signal. There is no redundant or filler wording.

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?

With no output schema, the description covers the expected return fields, and the input schema fully documents all parameters. The usage context is clear. It is missing only minor nonessential details like not-found behavior or whether the id is case-sensitive, but nothing an agent needs to make a correct call.

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 100%, so the input schema fully documents id, lang, and compact. The description restates the id formats and lists valid English names, adding minor convenience but not new semantic information beyond what the schema already provides.

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 uses a specific verb ('Retrieve') with an exact resource (a specific I-Ching trigram) and a distinct identifier method (number or English name). It also names the returned fields, making the tool's scope unambiguous. The singular 'specific' and the naming contrast with sibling 'get_iching_trigrams' make it easy for an agent to distinguish them.

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 description provides concrete usage context: 'Use this to understand the component trigrams of any hexagram.' This tells the agent when this tool is relevant, though it does not explicitly mention alternative siblings or exclusion conditions.

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