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

The description adds real value beyond the annotations: cost (2.5 credits), the 3-20 s duration constraint, and the async job nature. Annotations already cover the write/open-world profile, and nothing here contradicts them. It stops short of stating auth requirements or what the resulting task returns.

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, front-loaded sentences with no filler; purpose, cost, job nature, and endpoint in order. The trailing 'POST /videos/add-sound' is marginal but cheap and directional.

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 3-param mutation with no output schema, the description covers purpose, cost, constraints, async job behavior, and an analogous sibling for reference. An agent can invoke and follow up correctly; missing only explicit auth/prerequisite detail.

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 schema documents all three parameters, including the email account-selection logic and cropVideoOriginalSound. The description only adds the 3-20 s duration limit that constrains the video parameter, so baseline 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 (generate sound effects and ambience) and resource (a video), plus a concrete constraint (3-20 s). This distinguishes it from generic video tools, though it does not explicitly differentiate from the closest sibling, kling_lipsync, which also adds audio to 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?

'A job, like kling_text_to_video' implies the async job pattern and gives the agent a mental model for follow-up via kling_get_task. However, there is no explicit when-to-use/when-not guidance versus siblings like kling_lipsync or kling_text_to_speech, so usage is only implied.

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