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

With no annotations provided, the description carries the full burden and delivers: no download occurs, the call is free and does not consume the user's download quota, and the exact fields returned are enumerated. It also signals platform-specific limitations (public videos/reels only, view count 'when available'), which an agent needs to interpret results.

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?

Front-loaded with the core purpose, then structured into when-to-use, when-not-to-use, and a closing cost/ordering note. The long platform enumeration and the list of example utterances are somewhat redundant against the schema, but every block is scannable and purposeful.

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?

There is no output schema, so the description compensates by enumerating the returned fields (title, uploader, duration, view count, upload date, thumbnail, description, qualities, license). Combined with cost, ordering, and platform scope, an agent has everything needed to invoke and interpret this tool.

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?

Only one parameter, and schema coverage is 100% with the platform list already spelled out in the schema description. The description restates the same platform coverage, so it adds little meaning beyond what the schema provides; baseline 3 applies.

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?

States a specific verb (fetch metadata) and resource (video or audio track) and explicitly scopes it as 'WITHOUT downloading it,' which cleanly separates it from the sibling download_video. It also enumerates the returned fields, so an agent knows exactly what it gets.

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 explicit when-to-use triggers (sample user utterances about length, uploader, licensing, qualities) and an explicit do-not-use case routed to download_video. It further recommends calling this before download_video to confirm existence, pick quality, or check licensing.

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