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

Annotations already declare idempotentHint and destructiveHint=false, but the description adds real value beyond them: billing is by duration and resolution, and an uncertain result should be retried with the same inputs and idempotency key. It does not explain what happens to the source video or async task lifecycle, keeping it from a 5.

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?

Three dense sentences, front-loaded with the core action and no filler. Every clause carries information, though the middle sentence about coordinates is slightly terse.

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 13-parameter submission tool with no output schema and 0% schema coverage, the description is materially incomplete: it never mentions the videoUrl/mediaId oneOf requirement, removeAudio, coverUrl, or fileName, nor what the submission returns or how to track it. Given the complexity, this leaves the agent guessing on several required decisions.

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 0% across 13 parameters, so the description must carry the load but explains only x1/y1/x2/y2 (all-or-nothing rectangle) and idempotencyKey. Major inputs like videoUrl vs mediaId selection, coverUrl, fileName, and removeAudio are left undocumented anywhere.

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+resource: submitting a video to erase hardcoded subtitles or visual watermarks. This is clearly distinguishable from siblings like estimate_subtitle_cost or get_subtitle_task. It does not explicitly name the sibling it is not, so it falls short of a 5.

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 conditional usage for the rectangle params ('full-frame by default; provide all x1, y1, x2, y2 only for a user-supplied rectangle') and retry guidance, but never says when to choose this over estimate_subtitle_cost or remove_video_watermark, nor any prerequisite ordering. Usage is implied rather than routed.

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