Picture in picture

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

With no annotations, the description carries the behavioral burden. It goes beyond a generic 'overlay' statement by disclosing that the overlay's audio is dropped while the main video's audio is kept, and that the overlay disappears when its clip ends. It does not mention overwrite behavior or permissions, but covers the most relevant behavioral traits.

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 sentences, front-loaded with the core operation and example use cases. Every sentence adds information, with no filler or repetition of the title.

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 6-parameter transformation tool, the description plus schema covers the main behavior and an important edge case (overlay ends). It does not discuss scenarios like overlay longer than the main video or output overwriting, but those are secondary and not required given the schema clarity.

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 already covers all 6 parameters with descriptions and defaults, so the description adds little parameter-level detail. The audio and clip-end behaviors inform how overlay_path is treated, but that is not a substitute for parameter documentation. Baseline 3 is appropriate given full schema coverage.

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 action—'Overlay one video on top of another in a corner'—with concrete examples like webcam feed or reaction box. This clearly distinguishes it from siblings that overlay text, watermarks, boxes, or stack videos.

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?

Provides clear use-case context ('webcam feed or reaction box') and specifies the overlay behavior, but it does not name alternative tools or explicitly state when not to use this tool. Still, the context is strong enough to guide usage.

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