Inspect the certificates of a thing

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

Annotations already establish readOnly/idempotent/non-destructive, so the bar is lower, and the description still adds real behavioral content: it discloses exactly what is returned (certificates with status and expiry) and that inactive, revoked, expired and expiring-soon entries are flagged. It stops short of noting pagination or whether the check is point-in-time.

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 core behavior is front-loaded in one dense sentence. The second sentence about certificate expiry being a 'classic silent fleet outage' is motivational rather than operational and does not strictly earn its place, though it is brief.

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 read-only, single-parameter tool with no output schema, the description carries the return-value burden adequately by naming the listed fields and the flagged statuses. Nothing essential to correct invocation is missing, though the flag semantics (e.g., what 'expiring soon' means) remain undefined.

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?

Single parameter with 100% schema description coverage ('Exact AWS IoT thing name.'), so the schema fully carries parameter meaning. The description adds no syntax, format, or constraint detail beyond it, which is the correct baseline of 3.

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?

States a specific verb and resource: lists the X.509 certificates attached to a thing, plus the fields returned (status, expiry) and the flagged states. The resource is clearly distinct from every sibling (describe_thing, list_things, get_device_shadow), so an agent can disambiguate without opening the schema.

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?

Usage is only implied by the motivation sentence about certificate expiry causing silent outages; there is no explicit when-to-use, when-not-to-use, or named alternative (e.g., describe_thing for general thing metadata). An agent can infer intent but gets no routing guidance.

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