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

With no annotations, the description carries the full disclosure burden, and it does add genuinely non-obvious traits: browser-side processing, higher credit burn, Welcome-credit caps, and Day Pass exclusion. It still omits supported input formats, file-size limits, processing time, and where the resulting MP3 goes, which matter for a conversion tool.

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 purpose is front-loaded and easy to find, but roughly half the text is pricing boilerplate that reads as marketing copy and is duplicated conceptually with mioffice_pricing_info. There is also a stray double period ('before you use it..'), signalling unedited text.

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, no-output-schema, no-annotation tool, the definition covers billing eligibility well but leaves critical operational gaps: how the video is supplied (no input parameter exists), what formats are accepted, and how the extracted track is delivered. An agent knows the cost model but not the mechanics.

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 schema has zero parameters, which normally earns a baseline 4, but the description instructs the caller to 'choose the bitrate' — a choice that does not exist anywhere in the input schema. That creates a false expectation about the invocation surface and slightly undercuts an otherwise clean zero-param tool.

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 opening clause states a specific verb and resource: extract the audio track from a video and save it as MP3, which separates it from audio-format siblings like mio_video_aac_to_mp3 or mio_video_wav_to_mp3. However, it never names an alternative explicitly, so the differentiation is inferred rather than stated.

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 credit note ('uses more credits per run than the Document / Image / Scanner workspaces') gives an implicit cost-based tradeoff cue, but there is no explicit when-to-use, when-not-to-use, or named alternative. An agent can infer usage from the purpose but receives no routing guidance.

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