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

Annotations already cover readOnly/idempotent/non-destructive, so the description does not need to repeat safety. It adds real value beyond them: the security consequence that every returned key can log in to the machine, the fact that the call is free, and where new keys are created (console or POST /v1/ssh-keys) since no create tool exists among the siblings.

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?

A single dense sentence front-loads the resource and its fields, then moves to consumption and creation paths. The colon-and-parenthetical stacking makes it slightly packed, but no sentence is wasted.

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?

With no output schema, the description compensates by naming the returned fields, and it covers cost, side-effect freedom, and how keys come into existence. For a zero-parameter read tool, an agent has everything needed to call it and interpret the result.

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?

The tool takes no parameters, so there is nothing for the description to disambiguate; baseline for a zero-parameter tool applies. The description still usefully frames the output fields, though that is a return-value detail rather than parameter semantics.

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?

Names the exact resource (SSH public keys saved on the account) and even enumerates the returned fields (name, fingerprint, id). It distinguishes itself from the sibling instance_ssh_keys by naming the downstream consumers (rent_gpu's ssh_key_ids, instance_ssh_keys' add_ssh_key_ids).

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?

Usage context is explicit: this is the lookup to call when you need key IDs to pass to rent_gpu or to attach to an instance via add_ssh_key_ids. It does not state exclusions, but the alternative use case is clear enough from the named consumers.

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