Picture in picture

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

With no annotations, the description provides critical behavioral details: overlay audio is dropped, main video audio is kept, and overlay disappears when its clip ends. This goes beyond typical expectations and helps the agent understand side effects.

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 two sentences, front-loaded with the core purpose, and every sentence adds value (behavioral details). No redundancy or fluff.

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?

With no output schema and no annotations, the description covers purpose, key behaviors, and edge cases (overlay ending). It could mention what happens if the overlay is longer than the main video or default dimensions, but schema covers defaults. Overall, it's complete enough for a moderately complex tool.

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 covers all parameters with descriptions (100% coverage), so the description adds minimal extra meaning. The baseline of 3 applies because the schema already does the heavy lifting for parameter semantics.

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 overlays one video on another in a corner, with relatable examples (webcam feed, reaction box). This distinguishes it from sibling tools like add_watermark (image overlay) or stack_videos (side-by-side).

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 implies when to use this tool via the scenario examples, but does not explicitly contrast with alternatives. It's clear enough for an agent to infer use cases, but lacks explicit 'use instead of' guidance.

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