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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower. The description adds genuinely new context: the operation is free of charge and returns a fixed set of attributes (what it proves, how earned, requirements, tier, price, validity), which matters since there is no output 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?

A single front-loaded sentence that opens with the usage cue, then lists return content, then closes with the cost note. No filler or repetition.

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 zero-parameter, no-output-schema listing tool, the description supplies exactly what is needed: what comes back and that it is free. It does not mention ordering, pagination, or result volume, which is a minor residual gap for a tool claiming to return "every" type.

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 tool takes zero parameters, so there is nothing for the description to disambiguate beyond what the empty schema already shows. Baseline for a parameterless tool is 4.

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?

"Use to see every certificate type" gives a specific verb (see/list) and resource (certificate types), immediately distinguishing a catalog browse from per-certificate operations like check_certificate or list_certificate_signing_keys. It stops short of naming any sibling explicitly, so an agent must infer the contrast.

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?

"Use to see every certificate type" implies the browse-the-catalog use case, and the enumerated fields suggest it is a discovery/overview step. There is no explicit when-not guidance or reference to alternatives such as check_certificate, leaving selection logic implicit.

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