detect_video_faces

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

With no annotations, the description carries the burden of behavioral disclosure. It clearly says 'Trigger', implying an asynchronous operation, and indicates a backfill scenario. However, it does not mention idempotency, whether existing face tags are overwritten, or what the response indicates, which are potential gaps for a mutation-like trigger.

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 one concise sentence of 18 words. It leads with the action and resource, then adds the conditional context. There is no redundant information or filler.

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 (one parameter, no output schema, no nested objects), the description adequately covers purpose and usage context. It could be improved by noting that detection is asynchronous and how to verify results, but this is a minor gap given the straightforward nature of the tool.

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 100% with the parameter 'id' described as 'ID of the resource', which is generic. The tool description adds no additional parameter context. Since the single parameter is self-explanatory and the schema fully describes it, the baseline of 3 is appropriate.

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 action ('Trigger face detection') on a specific resource ('existing video asset') with a clear context ('for videos uploaded before video face tagging shipped'). This distinguishes it from sibling face-related tools like tag_video_face or get_asset_face_taggings, which handle tagging or querying rather than backfill detection.

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 explicitly scopes the tool's use to videos uploaded before the face tagging feature shipped, which tells the agent when this tool is appropriate. It does not name alternatives but the contextual exclusion is clear enough.

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