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

Annotations already establish readOnly/openWorld/idempotent, and the description adds real value on top: it discloses the return content (comparison image layout plus numbered component IDs) and an important constraint ('不依赖服务器草稿' – the full document must be supplied rather than relying on a server-side draft). It does not cover failure/limit behavior, but the additions are meaningful given annotation coverage.

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 tight, front-loaded clauses lead with the core action (generate PNG preview) before covering the optional reference and the input constraint. No filler; dense but each clause earns its place.

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 moderately complex tool (nested reference object, no output schema), the description adequately conveys inputs, the optional comparison mode, and the returned artifacts. The gaps are minor – width/height semantics – and the nested reference fields are documented in the schema itself.

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?

Top-level schema description coverage is 0%, so the description must carry the burden; it clarifies the meaning of 'document' (full document input) and 'reference' (optional comparison image). However, it says nothing about the width/height sizing parameters, so compensation is only partial, leaving half the top-level parameters unexplained.

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 states a specific verb and resource: generate an actual PNG preview from shared component geometry, and it describes the output (left reference / right scene comparison plus numbered component IDs). It clearly distinguishes the preview/compare role from siblings like export_scene or build_scene, though it never names an alternative explicitly.

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?

It gives one conditional cue ('可提供reference题图' – optionally supply a reference image for comparison) and a prerequisite ('输入完整document'), but it offers no explicit when-to-use/when-not guidance against the many related siblings (export_scene, review_scene, inspect_scene). Usage is implied rather than directed.

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