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 one genuinely useful behavioral fact beyond them – the output is produced by a real algorithm engine rather than an LLM, which tells the agent the result is deterministic and reproducible. It says nothing about how the chart_type value affects output or about any failure modes.

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?

Very short and front-loaded: the bracketed action tag comes first, then the use case, then the return value. No filler sentences. Slightly hurt by mixed Chinese/English phrasing and the tag restating the title, but it is economical overall.

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 simple two-parameter read-only text generator with full schema coverage, the essentials (what it does and what it returns) are present. Gaps remain around the accepted chart_type values and whether context is optional, which an agent must infer from the schema alone.

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% and both properties carry their own descriptions, so the baseline is 3. The description never mentions either parameter (chart_type or context), adding no meaning beyond the schema, though it also does not mislead about them.

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?

"【图注生成】" plus "用户有图要写图注、Figure legend" states a specific verb (generate/write) and resource (figure legend), and the description also names the output: legend text. Among the ~100 siblings there is no competing legend tool, so no explicit differentiation is needed; the purpose is unambiguous without opening the 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?

"用户有图要写图注" gives a clear triggering condition: the user has a figure and needs a legend written. It does not name exclusions or point to any alternative (e.g. act_forest_chart for drawing the chart itself), so it stops short of full when/when-not routing.

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