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

Annotations already declare it is a non-read-only, non-destructive, non-idempotent write. The description adds genuinely useful context beyond that: it is asynchronous ('returns an id right away'), the original is preserved, and the result lands in the Xenition library. It does not mention failure modes or credit/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?

Three tight sentences with the usage trigger front-loaded, followed by async behavior and data-safety notes. No filler, though the final sentence could be trimmed slightly.

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 a simple 4-parameter tool, an output schema, and full annotations, the description covers the trigger, the operation set, async behavior, and result location. Nothing an agent needs to invoke it correctly is missing.

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 75%, and the description independently explains the operation vocabulary (captions/enhance/matte/jumpcut) and ties language to captions. It adds meaning over the schema, though the title parameter and the URL source distinction are left to 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?

Names a specific verb (edit) and resource (an existing video) and enumerates the concrete operations supported: captions, enhance, matte, jumpcut. This clearly separates it from siblings like edit_image, edit_app, and create_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?

Opens with an explicit trigger condition ('Use this when the user wants an existing video improved') and names video_status as the follow-up for readiness. It does not explicitly name when NOT to use it (e.g. to create a new video, use create_video), so the routing is implied rather than fully closed.

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