video_chroma_key

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

No annotations are provided, so the description must fully disclose behavioral traits. It does not mention whether the tool modifies the input file, requires specific permissions, or has side effects. It implies output creation but does not clarify if it overwrites files or handles errors. This lack of transparency could lead to misuse.

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, with a clear one-sentence summary followed by a parameter list. It is front-loaded with the main purpose. However, the parameter descriptions in the args block could be integrated into the schema descriptions for better structure.

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 (not shown), the burden for return values is reduced. The description covers all parameters but lacks usage guidelines and behavioral details. For a tool with 5 parameters and 1 required, it is minimally complete but could be improved with context on when to adjust similarity/blend values.

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?

The schema has 0% description coverage for parameters, leaving the description to compensate. It explains `input_path` as absolute path, `color` as hex format with default green, `similarity` range 0.0-1.0, `blend` default, and `output_path` auto-generation. This adds significant meaning beyond the plain schema, though it could more explicitly define allowed formats.

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: 'Remove a solid color background (green screen / chroma key).' It uses a specific verb ('remove') and resource ('solid color background'). Among sibling tools, there is `video_luma_key` for luminance keying, but the description distinguishes by explicitly naming 'chroma key' and 'green screen', making the purpose unambiguous.

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 provides no guidance on when to use this tool versus alternatives like `video_luma_key` or `video_apply_mask`. It does not specify prerequisites, context, or when not to use it. The agent has to infer usage from the tool name and schema alone.

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