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

Adds substantial context beyond the annotations: per-language credit pricing, voice providers by tier, 1.25x timing fit, one rewrite, -18 dB ducking, output formats (MP4, SRT/VTT/JSON, optional M4A), 422 pre-charge validation, and refund-on-failure behavior. These details are consistent with readOnlyHint=false, destructiveHint=false, idempotentHint=true, and openWorldHint=true.

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 information is relevant, but it is delivered as one very long run-on sentence that opens with credit pricing rather than the action. The density and lack of paragraph structure make it harder to scan than necessary.

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 complex 13-parameter mutation with no output schema, it explains outputs, failure/refund behavior, and reuse options well. It does not explain how to supply source media via fileId vs mediaUrl, nor what maxCredits does.

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?

Explains several important parameters beyond the schema: keepOriginalAudio defaults to duck and can mute, audioTrack adds an M4A, and the two job/subtitle reuse paths. It leaves voice, fileId, mediaUrl, maxCredits, and sourceLanguage largely to the schema, which is acceptable at 62% coverage but not fully compensating.

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?

States a specific verb and resource: dubbing a video into another language, then details the full pipeline (transcribe, translate, voice, timing-fit, mix, return). This clearly separates it from siblings like translate (text-only), caption_video, and burn_captions.

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?

Gives useful prerequisites and reuse paths: call plan first for unsupported languages/tiers, reuse via transcriptionJobId/subtitles and translationJobId/translatedSubtitles. It also excludes voice cloning and lip sync, but does not explicitly name translate or caption_video as alternatives.

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