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

With no annotations provided, the description carries the full burden and does well: it discloses the credit cost (1 credit/time), supports multiple QR codes per image, returns an empty list when nothing is found, and notes the barcode limitation. It does not mention potential errors (e.g., invalid image), but for a simple decode tool this is sufficient.

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 concise and well-structured: the first sentence delivers the core purpose and key behaviors; the second adds a relevant limitation. Every sentence earns its place with no redundant filler.

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 decode tool, the description covers the essential aspects: input format (image via file_id or base64), output behavior (text list, empty list), and usage constraints (credit cost, QR-only). It lacks error handling details, but these are not critical for a standard tool invocation. The absence of an output schema is compensated by the explicit mention of returning a text list.

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 parameters are already well-documented. The description does not add extra parameter details beyond what the schema provides, but the schema already explains the mutually exclusive nature of file_id and data_base64. Baseline 3 applies when schema handles parameter documentation.

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's function: '识别图片里的二维码，返回文本列表' (recognize QR codes in images, return text list). It also specifies behavior for multiple QR codes and empty results, which distinguishes it from the sibling generation tools (e.g., qr_generate, qr_vcard).

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 implies when to use this tool (to decode QR codes from images) and explicitly states a major exclusion: '仅识别二维码(QR)，一维条形码识别暂不支持' (only QR, not 1D barcodes). It does not explicitly name alternatives, but among the sibling tools, all are generation-oriented, so the usage context is clear.

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