create_video

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

Annotations already cover the safety profile (non-read-only, non-idempotent, non-destructive), and the description adds genuinely useful context beyond them: the call is asynchronous and returns a render ID rather than a finished asset, so the agent must poll. It does not mention render duration, failure modes, or whether duplicate submissions create duplicate jobs (notably relevant given idempotentHint=false).

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 tight sentences, front-loaded with the action and followed immediately by the return contract and the required follow-up. Every clause carries information; nothing is redundant with the title or annotations.

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?

With no output schema, the description correctly carries the burden of describing the return value (a render ID, later a video URL) and the polling loop the agent must drive. For a nested-object, async render tool the picture is nearly complete, lacking only expected job duration or failure handling.

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%, with templateId, fields, and aspectRatio all self-documented including the nested field-value object and the default-ratio behavior. The description adds no parameter-level detail beyond what the schema already supplies, so the baseline of 3 applies.

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 ('Submit a video render job') plus the source of the render ('from a template'), which cleanly separates it from generate_image, render_carousel, and create_post among its siblings. An agent can identify the operation without opening the schema.

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 next-step routing: poll get_video_status until status is 'completed', then use the returned URL as post media — that is real when-to-use context and names the sibling to hand off to. It does not state when NOT to use it (e.g. versus render_carousel or generate_image for non-template output), which keeps it short of a 5.

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