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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds useful non-obvious context: it is the same catalog as desktop/mobile and it neither starts a job nor consumes tokens, which matters for cost-sensitive agent decisions.

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 tight sentences with zero filler. The primary purpose is front-loaded, and the cost/no-job constraint is placed last where it reads as a boundary condition rather than clutter.

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 zero-parameter, read-only listing tool with no output schema, the description fully covers what an agent needs: what is listed, what the entries contain, the catalog source, and the fact that calling it is free and side-effect-free. Nothing material is omitted.

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 there is nothing for the description to disambiguate; the baseline of 4 applies. No parameter guidance is needed or missing.

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 gives a precise verb+resource (list video upscalers) and enumerates the returned scope: provider routes, supported controls, and release availability. It also draws a clear boundary against the most confusable sibling by stating it does not start a job or spend tokens, which separates it from upscale_video.

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 description establishes clear context for when to reach for it (discovery/browsing before committing to an upscale) and effectively excludes the job-running case ('Does not start a job or spend tokens'). It does not, however, explicitly name an alternative tool such as upscale_video or list_video_models, so the routing is left slightly to inference.

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