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

Annotations only flag it as a non-read-only, non-destructive, closed-world write. The description goes well beyond that: per-second credit costs (3 kling / 20 vs 30 credits for 10s), the fact that without confirm it only quotes and with confirm it spends, resolution constraints, and the 30-second/50MB reference limits.

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-loads the purpose before the engine/pricing detail, and every clause carries information. It is a dense run-on paragraph rather than structured bullets, which costs a point but no sentence is wasted.

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 9-parameter, nested-object, enum-heavy tool with an output schema present, the description covers inputs, cost model, engine behavior and the confirm gate. Nothing needed to invoke it correctly is missing, and return values are handled by the output schema.

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%, so baseline is 3, but the description adds real meaning: default engine, credit math per engine, that prompt is read only by kling, and the three accepted driver input channels (upload id, https link, chat attachment) mapped to their parameters.

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 ('make a clip where the influencer repeats the movement of a reference video') and scopes it precisely to motion transfer, which cleanly separates it from create_clip, create_clips and create_scene_replace_clip. An agent knows exactly what this produces 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?

Explains the engine trade-off (kling follows movement and reads the prompt; wan is cheaper, keeps the background, ignores the prompt) and the quote-vs-spend contract via confirm. It does not explicitly say when to prefer a sibling like create_clip instead, so it falls short of a full 5.

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