Cut a rectangular region from a video using x/y coordinates and width/height, then save the result to a new file.
Crop a video to a rectangle. width/height/x/y in pixels; must fit inside the source frame.
| Name | Required | Description | Default |
|---|---|---|---|
| x | No | ||
| y | No | ||
| input | Yes | Path to the file (relative or absolute) | |
| width | Yes | ||
| height | Yes | ||
| output | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are supplied, so the description carries the full behavioral burden. "Must fit inside the source frame" usefully signals a hard constraint, but the description never says what happens on violation (error vs clamp), whether the output is re-encoded, or whether the input file is touched.
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 short sentences, zero filler, with the operation front-loaded and the constraint immediately after it. Nothing is wasted.
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?
A six-parameter mutation tool with no annotations and no output schema needs more than two sentences. Overwrite behavior, output file semantics, and failure modes on out-of-frame rectangles are all left unaddressed.
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 17%, so the description must compensate, and it does add units and a validity constraint for width/height/x/y. However, it says nothing about x/y defaulting to 0, the minimum of 2 for dimensions, or the input/output path roles that the schema only partly documents.
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?
"Crop a video to a rectangle" states a specific verb and resource, and the rectangle framing distinguishes it from the spatial sibling resize and the temporal sibling trim. It stops short of naming any sibling explicitly, so the differentiation is inferable rather than stated.
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?
There is no guidance on when to prefer crop over resize, or over extract_frame/thumbnail for static extraction. The only usage-adjacent statement is the geometric constraint, not a selection rule.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.