Resize / change aspect ratio

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

The description discloses the key behavioral implications of each fit mode (e.g., cover loses edges, contain pads with bars, blur overlays a blurred copy) and explains how focus affects cropping. With annotations only indicating non-read-only and non-destructive, the description carries significant burden and does so well. It could add more about encoding side effects, but the schema EncodeOptions covers those, and the core transformation behavior is transparent.

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 somewhat long but well-structured and front-loaded with a clear summary, then detailed sections for presets, fit modes, and alternatives. Every sentence adds value, though it could be tightened without losing critical information. The use of bullet-like formatting for fit modes enhances 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?

For a tool with 11 parameters and complex fit behavior, the description covers the essential decision points: presets, fit strategies, focus, and when to prefer an alternative. The output_path behavior is handled by the schema, and encode options are documented in the nested EncodeOptions, so the description is complete enough for an agent to invoke correctly. Minor gaps remain around default encoding behavior, but these are less critical.

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 73%, but the description greatly enriches parameter understanding: it enumerates specific preset names and their resolutions (e.g., reel, tiktok, story are 1080x1920), explains how aspect_ratio behaves when combined with width/height or used alone, and gives concrete examples of fit modes beyond the schema's brief descriptions. This adds substantial meaning beyond the structured schema.

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 states a specific verb and resource: 'Convert a video to a different resolution or aspect ratio.' It clearly distinguishes itself from sibling tools by explicitly recommending track_and_crop for talking-head videos where the subject must stay in frame, making its scope and unique purpose clear.

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 provides explicit usage guidance, including when to use a named preset versus explicit width/height/aspect_ratio, and for each fit mode what trade-offs exist. It also names an alternative tool (track_and_crop) for a specific use case, giving clear when-to-use and when-not-to-use direction.

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