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

With no annotations, the description carries the behavioral burden. It discloses that the tool validates multiple ID-card dimensions, which is useful, but it does not describe what the tool returns (e.g., validity boolean, extracted fields, error behavior) or how invalid inputs are handled. This is adequate but not rich.

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, compact sentence with the core purpose front-loaded, followed by a short parameter hint. Every element earns its place and there is no wasted wording.

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 tool has no annotations, no output schema, and no parameter descriptions in the schema, so the description must supply most usage context. It defines the purpose and the primary input, but it does not explain the second parameter, expected output, return format, or error behavior, leaving meaningful gaps for an agent that needs to interpret results.

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 0%, so the description must compensate. It adds meaning to the 'id' parameter by stating it is the 18-digit ID number, but it leaves the second parameter 'number' completely unexplained and does not clarify whether it is an alias, alternative, or ignored field. The parameter semantics are only partially addressed.

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 uses a specific verb ('校验' / validate) and resource ('中国大陆身份证号', Chinese mainland ID number), then enumerates exact validation dimensions: check digit, birth date, age, gender, and region code. This clearly distinguishes it from the sibling tools, none of which target ID card validation.

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 establishes a clear use case: validating an 18-digit Chinese mainland ID number. There are no direct sibling alternatives for ID validation, so explicit when-not-to-use guidance is not critical, and the context is clear enough for an agent to select this tool for ID-card checks.

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