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

With no annotations present, the description carries the full burden and does it thoroughly: it discloses input size limit, automatic GM OID branch detection, dual fingerprinting, the 'informational only' nature of validity status, library implementation details, and the exact failure error code 'Certificate parse failed.' This goes well beyond minimal safety and operational transparency.

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 dense and long, yet each sentence serves a purpose: input constraints, output inventory, GM-specific behavior, implementation notes, and error handling. Some implementation/bibliographic detail could be trimmed, but the structure is front-loaded with the core purpose and remains organized, so the length is justified.

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?

There is no output schema, so the description must fully disclose what will be returned. It enumerates all major return fields, specifies GM-only additions, gives exact hex formats for SM2 public keys, states validity status behavior, and provides the failure error code. For a complex certificate parser with one input string, this is complete enough for an agent to call and interpret the result.

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 baseline of 3 applies. The description repeats the PEM input and size constraint already in the schema but adds no new parameter-level meaning such as accepted encoding variants or handling of empty input. The schema and description are aligned, but the description does not elevate parameter understanding beyond the schema.

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?

Description begins with a specific verb and resource: parse X.509 certificates, and immediately distinguishes the two supported paths (international vs. GM SM2). The detailed list of returned fields makes the tool's scope unmistakable and differentiates it from sibling cert_verify by framing the operation as parsing rather than 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 use case is implied: 'parse X.509 certificate' clearly signals an analysis/parsing task rather than verification. However, the description never explicitly states when to prefer this over cert_verify or any other sibling, and there are no exclusionary conditions. It provides clear context but no formal when/when-not guidance.

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