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

readOnlyHint=true already establishes this as a safe read, so the description's job is lighter. It adds the underlying API mapping (GET /ssh_keys), which is modestly useful, but says nothing about pagination behavior, default page sizes, or result ordering despite four paging/filter params.

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 resource and its use case, then the API endpoint. Nothing is redundant and no filler is present.

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 list tool with full schema coverage and no output schema required, the description is largely sufficient. It could still note pagination defaults or that an empty list is valid, but no critical calling information is missing.

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 name, page, per_page, and label_selector all documented in-schema, so the schema carries the semantic load. The description adds no parameter-level meaning, making the baseline 3 appropriate.

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 (list) and resource (SSH public keys) plus a concrete purpose: keys available to inject when creating a server. It does not explicitly differentiate from the sibling hetzner_get_ssh_keys (singular retrieval) or hetzner_create_server, which consumes these keys, so it falls short of the 5 bar.

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?

No when-to-use guidance, no mention of the alternative hetzner_get_ssh_keys for fetching a single key, and no exclusions. The 'available to inject' phrase hints at context but stops short of routing the agent.

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