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

Annotations already declare readOnlyHint=true, so safety is covered; the description adds real context beyond that — what the payload contains (per-name mode auto/custom, days left, last reissue, blocked-reissue window) and the operational fact that renewal is automatic. That automatic-renewal note is exactly the kind of behavior an agent needs when deciding whether to escalate to a reissue call.

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?

Two sentences, front-loaded with the resource and then a dense enumeration of returned fields; nothing is filler. Slightly list-heavy, but each clause maps to a distinct output attribute rather than repeating structured data.

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?

An output schema exists, so return-value explanation is optional, yet the description still summarizes the shape enough to make the tool self-explanatory for a one-parameter read. Nothing an agent needs to invoke it correctly is missing; only an explicit pointer to tls_reissue for the blocked-reissue case would round it out.

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 required serviceId at 100% schema description coverage, so the schema already handles the parameter. The description adds no scoping or format detail for serviceId; baseline 3 is correct when the schema does the work.

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 names the resource precisely — certificates of a service, per served name, with mode, expiry and reissue state — so an agent knows exactly what it retrieves. The verb is only implied ('Certificates of a service' rather than 'Get/Show'), and it never names tls_reissue as the mutation counterpart, so sibling differentiation is left to inference.

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 closing line 'Certificates renew on their own' implies this is the inspection tool and manual reissue is usually unnecessary, which nudges the agent toward tls_status over tls_reissue. However, there is no explicit when-to-use/when-not statement and no named alternative, so usage is only implied.

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