extend_video

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

With no annotations, the description carries the full burden for behavioral disclosure. It states the tool returns a task id, status, and output URLs, which hints at asynchronous behavior, but it does not disclose that the task may initially be pending, that wait/polling parameters exist, or that this is a paid/compute-consuming operation. Minimal behavioral context is provided.

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 a single, front-loaded sentence with no wasted words. It efficiently conveys the primary action and return behavior. Excellent conciseness.

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?

Despite having 9 parameters, 3 required, no output schema, and no annotations, the description provides only the basic purpose and return format. It lacks usage guidance, parameter explanations, and asynchronous behavior details. This is inadequate for a tool of this complexity.

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 description coverage is only 22% (only wait and model have descriptions). The tool description adds no explanation for required parameters such as source_task_id, prompt, or output_resolution. It fails to compensate for the low schema coverage, leaving the agent without parameter meaning.

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 creates a Runway task on RunAPI specifically for extending a video. The parenthetical '(extend video)' distinguishes it from the sibling text_to_video tool. However, it does not explicitly name the alternative or contrast with text_to_video, so it falls short of a perfect 5.

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 provides no guidance on when to use this tool versus alternatives like text_to_video. It does not mention any preconditions, exclusions, or specific scenarios. This is a clear gap, especially given the sibling tools.

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