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

With no annotations, the description carries the burden of behavioral disclosure. It adds useful context about in-browser processing and credit usage, but it does not describe output behavior, such as whether a file is returned or how the extracted MP3 is delivered. This partial disclosure warrants a mid-range score.

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 first sentence crisply states the purpose, front-loading key information. The remaining sentences detail credits and pricing, which are relevant for usage but could be more concise; four sentences on plans is slightly verbose but not unreasonable.

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 zero-parameter tool with no annotations and no output schema, the description covers purpose and major operational constraints. However, it omits details like supported input video formats and output delivery mechanism, leaving notable gaps for an agent to understand the full tool behavior.

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 tool has zero parameters, and the input schema is empty. Per rubric, 0 params gives a baseline of 4. The description adds no parameter details because none are needed; the lack of parameters is self-evident.

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 clearly states 'Video to MP3 — Extract audio from video files' with a specific verb and resource, making the tool's function unambiguous. Although it doesn't explicitly compare to sibling tools, the output format (MP3) naturally distinguishes it from video-to-video converters.

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 provides credit-cost and eligibility constraints ('uses more credits per run', 'Day Pass does not include this workspace') but offers no guidance on when to choose this tool over alternatives. It lacks explicit when-to-use or when-not-to-use scenarios, which is a significant gap for an agent selecting among many media tools.

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