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

Annotations only declare readOnly=false, destructive=false, openWorld=true. The description adds the async job model (returns dubbing_id + status 'working', re-call to collect), the billing rule (per minute at dub start, token quote, free collection), and where the output lands (your library). This is genuinely new behavioral context beyond the annotations.

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?

Front-loaded with the core action, then the async/collection workflow, then billing and returns. Dense and every sentence carries information, though the language-code enumeration makes it longer than strictly 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?

No output schema exists, and the description compensates by naming the return fields (audio_url, duration_seconds, generation_id) plus the intermediate working-state payload. For a 5-param, no-required-args tool it covers start, resume, billing and output completely.

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 coverage is 100%, so the baseline is 3. The description adds meaning beyond the schema by expanding each language code to its language name ('es Spanish, fr French...') and reinforcing that source accepts a library id or public https link and that dubbing_id is sent alone. Marginal but real added value.

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 ('Say a recording again in another language... using ElevenLabs dubbing') and distinguishes itself from siblings like generate_speech, change_voice and transcribe_audio by naming the dubbing action and the speaker-preservation goal. An agent can tell exactly what this produces without opening the schema.

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 explicit conditions: pass source + target_language to start, leave source_language out to auto-detect, pass dubbing_id alone to collect a finished job, and only set speakers when you know the count. It does not name sibling alternatives to route against, so it falls short of a full 5.

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