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

Annotations already declare readOnlyHint=true, so the agent knows this is a safe read. The description adds the upstream endpoint (GET /ssh_keys) but does not disclose pagination behavior, return shape, or filtering semantics beyond what the schema states. With annotations carrying the safety profile, this is adequate but not rich.

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 that front-load the action and resource, then the upstream endpoint. The endpoint reference is mildly redundant but cheap; nothing is padded.

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 read-only list tool with full schema coverage and annotations carrying the safety profile, the description is nearly complete. With no output schema, the only minor gap is not hinting at the returned fields, which is acceptable for a list operation.

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%, with each of the four parameters (name, page, per_page, label_selector) already documented in the schema. The description adds no parameter syntax or semantics beyond the schema, so the baseline 3 applies.

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 ('List the SSH public keys') and adds useful scope ('available to inject when creating a server'). It does not explicitly distinguish itself from the sibling hetzner_get_ssh_keys, relying on the reader to infer list-vs-single from naming.

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 phrase 'available to inject when creating a server' implies the context in which the result is consumed, giving an implied use case. However, there is no explicit when-to-use/when-not guidance and no named alternative (e.g. hetzner_get_ssh_keys) to route between.

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