video_apply_mask

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

No annotations are provided, so the description bears the full burden of behavioral disclosure. It describes the mask semantics (white=visible, black=transparent) and the feather parameter, but it does not mention whether the operation is destructive, what happens to existing output files, or any permissions or format requirements. The description is adequate but not comprehensive.

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 description is concise (one introductory sentence followed by four parameter lines) and well-structured, with the core action front-loaded. Every sentence adds necessary information 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?

Given the existence of an output schema, the description does not need to explain return values. It covers the parameters adequately. However, it lacks information about prerequisites (e.g., video format compatibility) and potential error conditions. For a tool with moderate complexity, it is nearly complete but could be slightly more thorough.

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%, so the description must fully explain the parameters. It does so effectively: input_path and mask_path are described with absolute path requirements and mask color meanings, feather includes default and unit (pixels), and output_path explains auto-generation behavior. This provides clear semantic meaning beyond the schema's bare types.

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 clearly states the tool's action: 'Apply an image mask to a video with edge feathering.' It uses a specific verb (apply) and resource (image mask to a video), and the mention of 'edge feathering' distinguishes it from sibling tools like video_chroma_key (color-based) or video_shape_mask (shape-based).

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 does not explicitly state when to use this tool versus alternatives. While the action is clear, there is no guidance on when not to use it or which sibling tools (e.g., video_chroma_key, video_luma_key) might be more appropriate for different masking needs.

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