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

Annotations already declare readOnly=false, idempotent=false, destructive=false and openWorld=true, so the safety profile is covered. The description adds genuine behavioral context beyond that: per-format size ceilings (10 MB image, 30 MB video/audio, 50 MB url), the accepted MIME types, and the POST /assets endpoint. It stops short of saying what happens on re-upload or any rate 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?

A single dense sentence plus a short return-value sentence; formats, sizes, and transport options are front-loaded before the return semantics. Slightly packed with parenthetical lists, 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?

There is no output schema, so the description correctly compensates by stating that a Kling url is returned and where it can be reused. Combined with the annotations and fully documented schema, an agent has enough to call it; only re-upload/idempotency behavior is unstated.

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 the baseline is 3, but the description adds meaning the schema does not carry: the url path is capped at 50 MB, contentBase64 is intended for small files, and the format list maps onto the mimeType enum. That is real per-parameter selection guidance, not repetition.

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 (Upload) plus the resource (image/video/audio asset) and its destination (a Kling account), and enumerates the concrete formats accepted. This clearly separates it from siblings like kling_list_uploads and kling_delete_uploads, which operate on the same asset collection.

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 explains the output's purpose ('Returns the Kling url to use as an input (image, image_tail, video, audio, motionUrl, imageUrl…)'), which implies this is a prerequisite step for the generation tools. However, it never names a specific alternative tool or states when NOT to use it, so the routing guidance is only implied.

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