video_luma_key

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

With no annotations, the description bears full responsibility. It explains that pixels below threshold become transparent and that output_path is auto-generated, but omits side effects (e.g., if original file is modified), permissions, or performance implications.

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 single sentence for purpose followed by a structured argument list. It is front-loaded and easy to parse, though minor formatting improvements (e.g., bullet points) could enhance readability.

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?

Covers all parameters and basic behavior, but omits details about output format (e.g., alpha channel presence), video format constraints, and any operational nuances. Given simple tool complexity and existing output schema, it is minimally adequate.

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 descriptions are missing (0% coverage), but the description adds clear meaning: input_path as absolute path, threshold with range and effect, output_path with auto-generation behavior. This fully compensates for schema gaps.

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 explicitly states the tool masks out dark regions based on luminance, with a clear verb and resource. It distinguishes from color-based keying (e.g., video_chroma_key) by specifying luminance.

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?

No guidance on when to use this tool versus sibling tools like video_apply_mask or video_chroma_key. The description does not mention alternatives or context-specific usage.

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