video_overlay

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

With no annotations provided, the description carries the full transparency burden and does well: it discloses local processing, dependency on ffmpeg, bundled-font rendering, output contents (path, duration, resolution), structured errors, and dry-run behavior. It does not detail potential side effects like overwriting files or network timeouts for URLs, but it covers the main 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?

The description is tight and front-loaded, with the core purpose in the first sentence and supporting constraints in the following sentences. Every sentence earns its place, and there is no filler or repetition of schema content.

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 9-parameter tool with no output schema, the description adequately covers the main workflow, constraints, prerequisites, and return values. It could be slightly richer on how multiple overlays combine or what happens with URL inputs, but the visible guidance is sufficient for most agent decisions.

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 coverage is 100%, so the baseline is 3; the description adds meaningful value by grouping parameters into three feature families (logo, timed text, end card), stating the 'at least one of' constraint, and explaining text use cases. It does not redundantly restate schema details.

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 opens with a specific action ('Stamp a logo, timed text, and a branded end card onto a video') and clearly identifies the resource and scope. It also differentiates itself from siblings by emphasizing 'local ffmpeg, no credits' and its overlay-specific capabilities versus stitching or captioning tools.

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 gives concrete usage context: pass at least one of logo/texts/end_card, requires ffmpeg, and dry_run previews without running ffmpeg. It does not explicitly name alternatives or state when not to use the tool, but the 'captions you place yourself' phrase hints at a contrast with automated captioning.

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