download_video

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

No annotations provided, so description carries full burden. It discloses key behaviors: muxing video+audio to mp4, extracting m4a with audio_only, default save location (~/Downloads), browser-cookie riding for gated videos, and anonymous retry fallback. Missing some detail (e.g., what happens if muxing fails), but strong coverage for a tool with zero annotations.

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 dense paragraphs, zero wasted words. Front-loaded with the core purpose, then muxing behavior, then save/override options, then gated-content handling, and a closing sibling differentiation. Every sentence earns its place.

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?

Tool has real complexity (multiple input URL types, gated content, cookie handling, output format selection) and an output schema exists. The description covers all dimensions: what it downloads, output formats, save location, authentication/cookie handling, fallback behavior, and sibling differentiation. Complete for the tool's 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 0%, so description must compensate. It explains the audio_only=true flag (extracts m4a) and dest_dir (override save location), and reveals the MDBROWSE_DOWNLOADS env var as an alternative override. The url parameter is well-implied as a page or media URL. Doesn't cover every parameter exhaustively but the key semantics are present.

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?

Specific verb+resource: downloads video (or audio) via yt-dlp. Clearly distinguishes from download_document (plain files) and explains what yt-dlp handles that a plain download can't (HLS/DASH, YouTube/Vimeo, embedded players). Strongly differentiates from siblings.

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?

Explicitly states when to use this tool vs download_document — 'Use this for a <video>/embed a user wants to keep; use download_document for a plain file (PDF, image, dataset).' Also specifies environment variables (MDBROWSE_DOWNLOADS, MDBROWSE_YTDLP_BROWSER) and retry behavior for gated content.

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