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

With no annotations, the description carries the full burden. "Look up" implies a non-mutating read and the description does disclose the kinds of content returned (structures, variations, slot formulas, dialogue examples), but it says nothing about error behavior or the shape of the response beyond a keyword list.

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 front-loaded sentence with no wasted preamble. It reads as a dense keyword list rather than prose, which is efficient but slightly reduces scannability of the primary purpose.

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 and no annotations, the description covers what the tool retrieves (structures, variations, formulas, dialogue examples) adequately. It stops short of describing return structure, which the absence of an output schema would otherwise warrant.

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's schema description already shows the accepted formats (Chinese pattern with ellipses, or a pinyin slug like 'hai-shi-ba'). The description adds no further meaning about the parameter, so the baseline 3 applies.

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?

"Look up core Chinese grammar structures" gives a specific verb (look up) and resource (Chinese grammar), clearly distinct from get_hsk_vocabulary. The addition of "authentic cinema dialogue examples" blurs the line slightly with search_dialogue_clips, but the core purpose remains unambiguous.

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?

Usage is only implied by the verb "Look up" and the grammar-structure resource; there is no explicit when-to-use, when-not-to-use, or routing to the siblings get_hsk_vocabulary and search_dialogue_clips. An agent could reasonably infer the scenario, but nothing confirms it.

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