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 discloses link validity (6 hours), the high-quality muted video behavior, availability of additional formats, deciphered URLs, and billing cost per call. This is substantial useful behavioral context beyond a simple action statement.

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 compact and front-loaded with the core purpose, followed by essential constraints and a pointer to the muxer. Every sentence adds value: validity, formats, muted video caveat, muxing alternative, and billing. No filler or redundancy.

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?

For a tool with no output schema and no annotations, the description covers the main operational details: what it returns, how long links last, the muted-audio caveat, and how to handle the audio/video merge. It does not describe exact response structure, but the simple link-returning nature makes this acceptable.

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 already covers 67% of parameters with detailed descriptions for `filter` and `quality`, including acceptable values and defaults. The tool description does not add parameter-specific semantics, but it does clarify the overall output format and download-link behavior, which indirectly informs parameter usage. This is adequate but not exceptional.

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: 'Grabs Youtube download links directly from Google Video server' and explicitly mentions the output includes 'additional formats' and 'deciphered URL'. It clearly distinguishes this tool from metadata-focused siblings like get_info and the muxing-focused get_mux.

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 gives clear usage context: this tool is for obtaining direct download links, and it explicitly points to the `/mux` endpoint as the way to merge audio and video when needed. It does not explicitly state when not to use it versus get_info, but the download-focused purpose is unmistakable.

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