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

The description adds substantial behavioral context beyond the annotations: the URL expires in one hour, the upload must be a multipart POST using the returned fields and then the file as 'file', and the next calls to edit_scene and regenerate_scene are specified. It does not explain what happens on repeated calls or any permission requirements.

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 compact and front-loaded: the first sentence states the purpose and expiry, the second gives the upload protocol, and the third gives the follow-up workflow. Every sentence adds necessary information with no waste.

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?

Given the tool's simplicity, the presence of annotations, and the fully described input schema, the description is complete. It covers the purpose, expiry, upload mechanics, and the full downstream workflow, so an agent can invoke it correctly without additional context.

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 input schema already documents all three parameters thoroughly. The description does not add any new semantic details about video_id, scene_id, or clip_index beyond what the schema provides.

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: get a one-hour upload URL for the user's own start frame (PNG) for one clip of a rendered scene. This clearly distinguishes it from sibling tools like get_reference_upload_url or get_audio_upload_url.

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 clear context for when to use this tool: when the user wants to provide their own start frame for a clip. It also outlines the subsequent steps (upload, edit_scene, regenerate_scene), but it does not explicitly name alternative tools or state when not to use this one.

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