download_video

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It goes beyond a simple 'get download URL' by revealing that the URL is time-limited (valid for 1 hour) and only works for videos with 'completed' status. These are non-obvious behavioral traits that help the agent handle the tool correctly. It does not mention error handling or authentication, but the key behavioral constraints are effectively conveyed.

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 exceptionally concise: two sentences that immediately state the primary function, then add the two most crucial constraints (URL expiry and status requirement). Every sentence earns its place, with no redundant or filler content. It is front-loaded with the core purpose.

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's modest complexity (2 parameters, no output schema, no annotations), the description covers the essential contextual aspects: what it returns (a download URL), when it is valid (completed status), and a key time-sensitive behavior (1-hour validity). It does not cover error cases or advanced usage, but for a simple download-URL tool, the provided context is sufficient for an agent to select and invoke it correctly. A minor gap is the lack of guidance on what happens upon URL expiry, but overall it is fairly complete.

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 provides 100% description coverage for both parameters, including detailed meaning for 'variant' (video, thumbnail, spritesheet). The tool description does not add further parameter-level detail beyond what the schema already states. According to the baseline, when schema coverage is high, a score of 3 is appropriate because the description does not need to compensate.

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 uses a specific verb and resource ('Get a download URL for a completed video'), clearly stating what the tool does. It distinguishes this from siblings by adding a scoped condition ('completed' status) and a key detail (URL valid for 1 hour). This makes the purpose unambiguous and distinct from related tools like get_video_status or wait_for_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?

The description provides clear context for when to use the tool: it only works for videos with 'completed' status, which implicitly tells the agent to first check status (via get_video_status or wait_for_video) before calling download_video. It does not explicitly name alternatives or exclusions, but the status prerequisite is strong contextual guidance. Given the sibling list includes status-checking tools, this is helpful but not fully explicit.

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