Download Video

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

Annotations already indicate readOnly=false (write), openWorld=true (external interaction), and destructive=false. The description adds 'Uses yt-dlp with best quality mp4 format' and return path, but does not disclose behavior around file overwrites, failure modes, or network reliability. This provides some context beyond annotations but not rich detail, so a mid-range score is appropriate.

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 concise sentences, each delivering essential information: purpose, return value, and implementation detail. No fluff, front-loaded with the primary action, and all sentences earn their place. This is an example of efficient, well-structured description.

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?

With no output schema, the description appropriately covers the return value (path). The underlying tool (yt-dlp) and format are disclosed. The presence of sibling tool check_dependencies hints at prerequisites, but the description could be slightly more explicit about failure cases or dependency requirements. Overall, it is complete for a simple download tool given the rich schema and annotations.

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 100%, with each parameter (url, filename, output_dir) already documented clearly. The description does not add parameter-level details, but it does note 'best quality mp4 format', which implies the output format despite no format parameter. Given the high schema coverage, a baseline score of 3 is appropriate.

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 action ('Download a video from a URL to a local file') and the return value ('Returns the path'), distinguishing it from sibling tools like download_audio (audio-specific), get_video_info (metadata-only), and check_dependencies (environment check). The verb+resource construction is explicit and unambiguous.

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 usage context is implied by the tool's name and description (use for downloading videos), but there is no explicit guidance on when to choose this over download_audio or get_video_info, nor any mention of prerequisites like network access or yt-dlp installation. This is adequate but lacks exclusions or alternative recommendations.

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