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

The readOnlyHint annotation already establishes this as a safe read. The description reinforces that with 'Fetch' and 'GET /certificates/{id}', but adds nothing about error behavior (e.g., 404 for unknown id), authentication, or what is returned, so it goes only marginally beyond the structured metadata.

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 short sentences, front-loaded with the action and with zero filler. The efficiency is good, though the brevity partly reflects generic template content rather than tight, tailored phrasing.

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 one-parameter fetch with no output schema, the definition is barely adequate: it does not say what a successful call returns (a certificate object and its fields) or how failures manifest. The endpoint mapping helps, but an agent has no picture of the response shape.

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 coverage is 100% and the single 'id' parameter is fully documented in the schema. The description's 'by id' merely echoes that, adding no format or constraint details beyond what the schema already provides.

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 verb 'Fetch' and the endpoint '/certificates/{id}' identify the resource, but the prose itself only says 'a single resource by id' — generic template text that would apply to any getter. Specificity comes from the URL, not the description, and the plural tool name vs. singular title is a mild inconsistency.

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?

There is no guidance on when to use this rather than hetzner_list_certificates (to discover an id) or any other sibling; the agent gets no hint about prerequisites such as needing a valid certificate id. The endpoint implies a direct lookup but no usage context is stated.

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