download_video

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

The description discloses the 7-day URL expiration and the automatic URL lookup when video_id is provided. It does not mention auth or side effects, but since downloading is inherently non-destructive, the added context is valuable.

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?

Two sentences, front-loaded with the core purpose. Every sentence is informative, with no redundancy or filler.

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 simple download tool with no output schema, the description covers purpose, input methods, and expiration. A minor gap is that it doesn't explicitly state one of video_id or video_url is required (only output_path is marked required in the 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 parameters are already well-documented. The description adds meaning by clarifying the relationship between video_id and video_url, indicating they serve as alternatives.

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 the tool downloads a finished HeyGen video to a local .mp4 file, with a specific verb and resource. It distinguishes from sibling tools that create, generate, check, or list videos, and notes the two input methods.

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?

It indicates the tool is for finished videos and explains how to pass video_id or video_url. However, it does not explicitly mention alternatives or when not to use this tool, though the context implies it.

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