Set Upstream Keyer Mask

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

Annotations already declare the write/idempotent/non-destructive profile, and the description adds real context: the coordinate space is absolute screen space, outside the rectangle is hidden, and the default is full frame. It does not say whether omitted edge values are reset to default or left unchanged, nor how maskEnabled=false interacts with stored coordinates.

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?

Purpose, use case, coordinate system, and example are front-loaded and earn their place. The trailing 'Args:' block restates every schema parameter description verbatim at 100% coverage, which is redundant bulk an agent does not need.

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 7-parameter mutation tool with no output schema and annotations covering the safety profile, the description supplies everything needed to construct a correct call: ranges with frame-relative meaning, the full-frame default, and a concrete example. Return values are not needed since the call is idempotent and the effect is described.

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 goes beyond the schema by mapping values to frame edges ('left edge to right edge of frame'), stating the full-frame default set, and giving a worked example combination. It doesn't clarify what happens to edges left unspecified on a partial update, which is the remaining ambiguity.

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 and resource ('Set the screen-space mask (clip region) for an upstream keyer') and immediately defines what the mask is ('an absolute rectangle on the output frame'). This clearly separates it from siblings like atem_set_usk_dve or atem_set_usk_sources, which configure other aspects of the same keyer.

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?

'Use this to clip a DVE overlay to a specific region of the screen (e.g., one cell of a grid layout)' gives a concrete use case and the intent behind the tool. It stops short of naming when NOT to use it or pointing to a specific alternative sibling (e.g., DVE position/scale vs. mask), so it lands at clear-context-without-exclusions.

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