generate_thumbnail_grid

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

With no annotations provided, the description carries the burden of behavioral disclosure. It explains the output format (JPEG contact sheet) and layout (evenly-spaced grid), but does not mention side effects, overwrite behavior, permissions, or errors. This is minimal but sufficient for a straightforward generation tool.

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 concise sentences provide the core function and a use case. No wasted words or repetition of schema details.

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?

The description covers purpose, use case, and output format. Given the schema fully documents parameters and there's no output schema, this is fairly complete. It could mention that thumbnails are sampled evenly across the video duration, but that's a minor gap.

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 100%, so the schema already documents all four parameters. The description adds 'evenly-spaced' and 'grid' but doesn't explain parameter semantics or defaults beyond the schema, so it stays at the baseline of 3.

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 function with a specific verb ('generate') and resource ('contact-sheet image with thumbnail frames'). It differentiates from sibling tools like extract_frames by describing a grid-based overview rather than individual frame extraction.

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?

It provides a usage context ('useful for getting a quick visual overview of a video'), indicating when to use it. However, it does not explicitly mention alternatives or when not to use it, so it falls short of the highest bar.

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