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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description still adds real context beyond them: the call works without a key (auth requirement) and it discloses the required permission scope 'catalog:read'. It also notes the payload carries each image's default SSH user, which is behaviorally useful.

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 tight sentence plus a permission parenthetical — no padding or repetition. The ordering is slightly off, since it opens with what an image is rather than what the tool does, but the text is appropriately sized for a zero-arg list call.

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 parameterless read with no output schema, the description supplies the essential extra facts an agent needs: no key required, the permission scope, and one field present in the results (default SSH user). It stops short of confirming what else each entry contains or that the full catalog is returned.

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 zero parameters, so the baseline of 4 applies; there is nothing for the description to disambiguate. The one parenthetical ('with its default SSH user') describes returned content rather than an input, so it does not add parameter meaning.

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 defines the resource ('Operating-system image installed on each GPU product') but never states the action — that this tool lists/returns the available OS images. An agent must recover the verb from the name and title. It also gives no differentiation from the neighboring catalog list tools such as gpucloud_list_templates or gpucloud_list_products.

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?

'Works without a key' is a faint usage hint (usable unauthenticated), but there is no when-to-use framing, no exclusions, and no pointer to the alternatives among the many list_* siblings. The agent gets no routing guidance.

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