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

Annotations already declare the tool as read-only, idempotent, open-world, and non-destructive. The description adds substantial behavioral context beyond annotations, including paid-only pricing, per-minute charging, minimum billing, the x402 quote-first payment flow, prepaid credits authentication, and that charges occur only when a transcript is returned.

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 dense but front-loaded: purpose, outputs, supported formats, pricing, payment mechanics, and exclusions all appear in a logical order. Every clause carries operational value for calling the tool correctly.

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 usefully explains the returned fields: transcript, detected language, timestamped segments, and optional SRT/VTT subtitles. It also covers file constraints, pricing, payment flow, and unsupported formats, leaving little an agent needs to infer.

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 schema already documents all six parameters. The description reinforces audio_url, format, and task=translate but does not add new semantics for vad, prompt, or language beyond what the schema provides, so the baseline 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 states a specific verb and resource: speech-to-text for a public MP3 or WAV file. It also names the primary outputs (transcript, detected language, timestamped segments, optional SRT/VTT) and the translate variant, so an agent can understand exactly what the tool does.

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?

It gives explicit supported inputs (public MP3/WAV, up to 30 minutes), exclusions (not m4a, ogg, flac, or webm), and the operational payment flow: call without payment for a quote, then retry with x402 payment metadata or a prepaid credits key. This is strong when-to-use and when-not-to-use guidance.

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