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

Annotations already establish the tool is read-only, idempotent, and non-destructive, so the bar is lower. The description adds meaningful context by stating the output is raw TOON text and enumerating what type of information it contains (required/optional params, ranges, enums).

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?

Both sentences earn their place: the first states what the tool provides and the second gives a clear directive for when to use it. There is no wasted verbosity or redundancy with the schema.

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?

The tool is simple, has no parameters, and its output format is described as raw TOON text. The description covers the tool's purpose and content well enough for an agent to know whether and when to call it before invoking `video_upscale`.

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 has zero parameters, so the baseline is 4. No parameter information is needed, and the description appropriately focuses on the returned catalog content instead.

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 identifies this as a catalog of video upscale modes, making the tool's purpose clear and linking it directly to `video_upscale`. It lacks a strong imperative verb like 'lists' or 'returns', but the name and 'catalog' semantics sufficiently communicate the resource and scope.

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 explicitly says 'Read before calling `video_upscale`', giving clear timing context relative to its main sibling. It does not mention when not to use it or recommend alternative tools, but the guidance is specific and actionable.

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