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

Annotations only declare readOnlyHint=false and destructiveHint=false, leaving the sync/async profile and billing undisclosed. The description adds real value: it is synchronous, returns a ready audio_url with no job_id to poll, and is consent-sensitive. The billing-by-text-size behavior is largely carried by the get_cost parameter description rather than the main text.

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?

Two compact sentences with the core purpose and the sync/no-job_id distinction front-loaded. The em-dash asides are slightly dense but every clause carries information; nothing is wasted.

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?

With no output schema, the description usefully states the return shape (ready audio_url). Combined with annotations covering the safety profile and a fully documented schema, an agent has enough to call it correctly; only the explicit sibling alternatives remain unaddressed.

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 fully documents text, voice_id, project_id, get_cost, and provider, including the provider cross-check and the billing rationale. The description adds little beyond this, so the baseline 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?

States a specific verb (Speak) and resource (text in a project's cloned voice), and explicitly distinguishes itself by being SYNCHRONOUS with a ready audio_url and no job_id. It also ties itself to its sibling lab_voice_clone, so an agent can route between cloning and speaking without opening either 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?

Conveys when to use it implicitly (to voice text through a cloned voice) and adds a consent constraint ('only speak text you have the right to put in that voice's mouth'). It gives provider guidance ('you do not pick it'), but never explicitly contrasts with alternative TTS siblings like lab_dub_tts or lab_dub.

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