download_video

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

Describes download destination ('Saves into ~/Downloads by default'), playlist refusal to avoid accidental full downloads, and required external tool. Adds context beyond annotations (readOnlyHint=false, destructiveHint=false).

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?

Four sentences, each serving a distinct purpose: action and scope, default location, safety behavior, dependency. No redundant or vague statements.

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?

Covers core behavior, defaults, playlist safeguard, and external dependency. No output schema needed; description is sufficient for an agent to use the tool correctly.

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% (baseline 3). Description adds context for allow_playlist (refusal unless set) and output_dir (default ~/Downloads). Enhances understanding of parameter behavior beyond schema.

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?

Clearly states verb 'Download', resource 'video from a URL', and scope 'YouTube and hundreds of other sites via yt-dlp'. Distinguishes from sibling 'get_video_info' which retrieves info only.

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?

Provides guidance on playlist handling ('Refuses playlist URLs unless allow_playlist is set') and dependency ('yt-dlp must be installed separately and reachable on PATH'). Implicitly differentiates from sibling by action (download vs info).

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