video_generate

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

Annotations already declare a non-readonly, non-idempotent, open-world, non-destructive write, and the description goes well beyond them: real billing (~$0.10/sec of 720p, no free tier), required user confirmation, the 8-second clip limit, the wait_seconds timeout path, and where the file lands. The only missing piece is what happens on failure or whether a timed-out render is still billed.

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?

Front-loaded with the verb, cost warning, and chaining rule before the Args block; the Args/Returns structure is easy to scan and each parameter line adds new information. Minor drag from the model/provider name ('Gemini Omni Flash through the Gemini API'), which doesn't help an agent decide or call.

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 costly, slow, open-world generation tool, the description covers cost, latency/timeout, output location, follow-up tools, and every parameter. An output schema exists, so the brief Returns summary is sufficient rather than redundant.

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 0%, so the description must carry all eight parameters — and it does, with meaning the schema cannot convey: prompt structure with a worked example and timecode sequencing syntax, first_frame/last_frame as start/end anchors, reference_images capped at 3 for character consistency, and the default file-name rule.

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 ('generate a short video with native sound from a text prompt') plus the concrete output (an .mp4 in GEMINI_PRO_OUTPUT_DIR). It explicitly separates itself from siblings by naming video_edit for extension and flow_make_video as the credit-based alternative.

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?

Gives explicit when-to-use conditions (one call = ~8s clip; chain video_edit for longer), names a concrete alternative (flow_make_video, gated on browser tools being enabled), and adds a mandatory pre-call step: confirm cost with the user. Exclusions and routing are both present.

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