veo_extend_video

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

No annotations provided, so description carries the burden. It mentions extending continues a previously generated video and returns a task ID and new video info. It does not disclose side effects like whether the original video is modified, but it implies it is not by requiring the source not be an extended video.

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?

Very concise: two sentences for purpose, a bullet list for usage, and a one-line returns section. No unnecessary words.

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 parameter count and schema coverage, the description is fairly complete. It explains what the tool does, when to use, and what it returns. Could mention how length is determined or that the original video remains unchanged, but not 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 description coverage is 100%, so baseline is 3. The description adds context about the video_id constraint and model support, but does not significantly add beyond the 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 clearly states the tool's action: extending a video by adding more content. It specifies the supported models (Veo 3.1 series) and distinguishes it from sibling tools like veo_text_to_video and veo_image_to_video.

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?

Provides explicit 'Use this when:' bullet points for making a video longer, adding content, or guiding next steps. Does not explicitly state when not to use, but the list effectively gives criteria.

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