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

No annotations are supplied, so the description must carry behavioral context; it does disclose browser processing, higher credit consumption, limited welcome credits, Day Pass exclusion, and the shared credit-pack model. It also indicates a downloaded MP4 copy rather than modifying the source, but it omits input limits, supported formats, and privacy/retention details.

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?

The core purpose is front-loaded in one sentence, but the definition includes a stray double period and a long pricing/credit paragraph that is largely workspace-level boilerplate. Some of that pricing context is useful, but it is not tightly edited for this specific tool.

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 no-parameter, no-output-schema tool, the description covers purpose, workflow, output type, and billing constraints. It is reasonably complete, though it could say more about the interactive launch behavior and file constraints.

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?

There are zero parameters, so the baseline is 4 and the empty schema needs no further description. The description does not add parameter semantics because none exist.

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 opening sentence names a specific verb and resource ('Crop a video') and adds differentiators: movable rectangle, aspect-ratio presets, and MP4 output. It does not explicitly contrast with nearby siblings such as mio_video_trim or mio_image_crop, so it is clear but not fully sibling-aware.

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 gives a workflow ('Choose the area to keep, check the framing, and download an MP4 copy') but never states when to use this crop tool instead of trimming, resizing, or rotating. No exclusions or alternatives are named.

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