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

Annotations are all false, so the description carries the burden. It discloses that this is a 'Paid render' and that it returns the served URL, which are useful behavioral traits. However, it does not elaborate on potential side effects, resource consumption, or any failure modes. It adds some value beyond annotations but is not exhaustive.

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 sentences with the core purpose front-loaded. The second sentence is longer but packs essential engine/mode details. No filler words; every clause contributes value. It is concise but not overly terse, balancing completeness with brevity.

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 has no output schema, so the description correctly explains the return value ('returns the served URL'). It also covers the two engine variants and the mode option, which are central to correct usage. It does not mention input video format constraints or any preconditions, but for an upscale tool with a single required parameter, the description is adequately complete.

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 coverage is 100%, so the schema already documents each parameter. The description adds meaningful semantic context by explaining the engine values ('Topaz' vs 'flux') and the mode's purpose ('creative' detail-enhancement pass). This goes beyond the schema's terse descriptions and helps the agent choose appropriate values.

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 action (upscale a video), the exact resolution multiplier (2x), and the intended use case (final delivery). It also names two engine variants, which further distinguishes the tool's scope. The purpose is unambiguous and not a restatement of the title.

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?

Provides clear guidance on when to select each engine: the default Topaz for faithful precision upscaling, and flux when the user explicitly asks for the FLUX upscaler or wants added detail. This is explicit context for engine choice, though it does not mention when to use an alternative tool (e.g., clip_video or edit_video) instead of upscaling.

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