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

Goes beyond the annotations by disclosing that the operation is asynchronous and consumes credits — neither is inferable from readOnlyHint=false/destructiveHint=false/openWorldHint=true. It stops short of stating whether credits are refunded on failure or any rate limits.

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, zero waste: the what/how comes first, then the async-plus-cost-plus-next-step facts. Nothing is repeated from the schema or annotations verbatim.

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?

An output schema exists, so return values need not be explained, and the description covers the async lifecycle, cost, and the follow-up tool. The remaining gap is failure/timeout behavior and credit refund policy, which matter for a paid async job.

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 description coverage is 100%, so the schema already explains resolution enum semantics (short side vs long side), clip start/end, and video_file_path formats. The description adds only a light restatement ('selected output resolution', 'segment') — baseline 3 is appropriate.

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 verb ('Upscales') and resource ('a supplied video segment') plus the key outcome (preserving aspect ratio, selected output resolution). The 'video' resource cleanly separates it from the sibling upscale_image without needing to name it.

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?

Explicitly says it starts a background job and returns a project id 'for wait_for_video_project', which routes the agent to the correct follow-up tool. It does not discuss when to prefer upscale_video over restyle_video or edit_video, so the alternative-selection guidance is only partial.

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