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

The description discloses substantial behavior beyond annotations: it takes the largest fitting crop, centers on focus, clamps to the frame, passes audio through, and returns the output path plus new dimensions. It also notes that missing output parent folders are created. These details meaningfully explain how the tool behaves at runtime.

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 sentences pack in the operation, examples, focus behavior, clamping, audio handling, and return value. The most important information is front-loaded, and every sentence contributes without redundancy.

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 4-parameter tool with a full schema and no output schema, the description covers the operation, parameter semantics, behavioral edge conditions, and return values concisely. No critical information needed to invoke or understand the tool is missing.

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 baseline is 3, but the description adds useful parameter semantics: it clarifies that `aspect` is interpreted as the largest crop that fits, and that `focus` is in source pixels with a top-left origin and defaults to center. It also explains how `output` is derived by default.

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 uses a specific verb ('crops') with a specific resource ('a video') and a clear goal ('to a target aspect ratio ... around a focus point'). It differentiates itself from media siblings like video_trim, video_concat, and video_export_gif by emphasizing aspect-ratio cropping and focus-point centering for social clips.

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 phrase 'for social clips' gives clear use context, and the mechanics of aspect-ratio reframing make the tool's niche obvious. It does not explicitly name alternatives such as video_trim or video_blur_region, or state when not to use it, so it stops short of a full when/when-not comparison.

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