kling_extend_video

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

No annotations are provided, so the description carries the full burden. It states the tool extends a video by adding content after the original ends and returns a task ID and video info. However, it does not disclose potential side effects, required authentication, rate limits, or asynchronous behavior. This is adequate but minimal.

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 short and front-loaded with the main action. It is structured with a paragraph, bullet list of use cases, and a returns line. There is slight redundancy (e.g., 'Extend an existing video' then 'This allows you to continue'), but overall it is efficient and earns its place.

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 has 6 parameters (2 required) and an output schema, the description explains the core functionality, appropriate use cases, and mentions the return value. It could be improved by noting prerequisites (e.g., having a video_id from a previous generation), but it is largely complete for an AI agent to use.

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?

The input schema has 100% description coverage, with each parameter detailed (e.g., video_id from previous generation, prompt for continuation). The description does not add substantial extra meaning beyond what the schema already provides, meeting the baseline for high schema coverage.

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 clearly states it extends an existing video with additional content, continuing motion after the original ends. This distinguishes it from sibling tools like kling_generate_video which creates new videos from scratch, and kling_generate_motion which likely focuses on motion generation.

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 includes a 'Use this when:' section listing three specific scenarios: video too short, want to continue story, building longer video piece by piece. This provides clear context but does not explicitly state when not to use or mention alternatives, though the sibling tools are distinct enough.

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