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

Annotations provide readOnlyHint=true, and the description adds useful context beyond that: it is a non-destructive conversion, it returns an MP3 file, and it costs 30 points per call. No contradiction with the annotations was found.

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 short and the core action is front-loaded. The Korean sentence repeats the English content, which is slightly redundant for an AI agent, but the overall structure remains compact and the cost note is clearly separated.

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 one well-documented parameter and no output schema, the description sufficiently explains the input, output, and cost. An agent can determine what to pass and what to expect, so nothing critical is missing for correct invocation.

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%, so the video_url parameter is already fully documented with allowed MIME types and the 200MB limit. The main description adds no additional parameter-level meaning, so the 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 uses a specific verb ('Extract') and clearly identifies the resource ('audio track of a video file') and output format ('MP3'). This naturally distinguishes it from sibling tools like download_youtube_video (returns a video file) and extract_video_thumbnail (returns an image).

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 intended use is clear: when the user needs the audio of a video as an MP3, this is the tool. However, it does not explicitly say when not to use it or compare it with alternatives such as download_youtube_video or stt.

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