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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals that output is saved to a file transfer station and returns a download URL, and that failures automatically trigger a refund ('产物存入文件中转站返下载 URL。失败自动退款。'), which adds useful context beyond the schema.

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 a single sentence that is front-loaded with the core purpose and includes critical operational details (cost, output, refund). Every clause contributes, with no redundancy.

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?

The description effectively covers the tool's purpose, output, and error-handling policy. Combined with a comprehensive schema covering all parameters, it provides sufficient context for a tool with no output schema and no annotations. Minor omissions like URL lifetime or explicit parameter examples do not significantly hinder usability.

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?

The input schema already describes all 7 parameters with detailed explanations (100% coverage), so the baseline is 3. The description adds no parameter-specific semantics, but also doesn't need to since the schema is thorough.

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 clearly states the tool generates a PNG QR code from text/URL ('把文本/URL 生成二维码 PNG'), specifying the action, input, and output format. It distinguishes from siblings by mentioning PNG specifically, though it doesn't explicitly contrast with alternatives.

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 no guidance on when to use this tool versus its siblings (e.g., qr_vcard, qr_wifi, qr_svg). It only describes the tool's own function and pricing, leaving the agent to infer applicability from the tool name and sibling names.

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