Make Spotify Canvas

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

With no annotations, the description carries the full burden and does well: it discloses the output is silent, the exact resolution/aspect, the 3-8s duration band, that videos are cut from `start` and centre-cropped, and that images get a slow seamless zoom loop. It does not mention dependency on ffmpeg-like tooling or error behavior for unsupported inputs, but the transformation semantics are unusually well surfaced.

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, zero filler, and the resulting artifact specification is front-loaded before the input-handling detail. Every clause carries information.

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 4-parameter, 1-required tool with no output schema or annotations, the description covers input types, output format, duration constraints, and divergent processing for video vs image. Only failure modes and overwrite behavior when `output` collides are left unstated.

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 schema already documents all four parameters, making 3 the baseline. The description adds modest value by clarifying that `start` triggers cutting and that cropping is centre-based for video, but does not explain how `output` interacts with the default location or the interaction between `start` and `length` limits.

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 verb and resource ('Turn a local video clip or image into a Spotify Canvas') and pins the exact output artifact: silent 1080x1920 9:16 MP4, 3-8 seconds. This is clearly distinguishable from siblings like create_ai_music_video or video_specs, which concern generation/specification rather than local conversion of an existing asset.

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 'local video clip or image' framing implies the context of use (converting an existing local asset), but no sibling is named and there is no explicit when-not guidance. An agent must infer that this is the conversion tool rather than an AI-generation one.

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