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

readOnlyHint=true already tells the agent this is a safe read, so the description carries no safety burden. It adds nothing further: no not-found behavior, no error semantics, no indication of what the response contains. For a fetch tool with annotations, this is the minimum.

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, front-loaded sentences with no filler or redundancy. It is efficiently structured, though partly because it says so little.

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 simple single-id fetch this is thin: with no output schema, the description should at least hint at what is returned or how failures surface, and it does neither. It leaves the agent with no more context than the schema and title already provide.

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% and there is only one parameter, so the schema already documents 'id' as the numeric resource id. The description adds no meaning beyond that baseline (e.g., no mention of where ids come from or how to find them).

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 says 'Fetch a single resource by id,' which is a generic verb+resource pairing that only becomes specific via the appended API path 'GET /ssh_keys/{id}'. The tool name and title say 'SSH key,' but the description itself never names the resource, and it does little to distinguish itself from sibling getters like hetzner_get_server or hetzner_get_certificates.

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 vs. alternatives such as hetzner_list_ssh_keys or hetzner_get_server. No prerequisites, no mention of what id values are valid beyond the schema, and no exclusions.

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