List TTS voices and providers

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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered elsewhere. The description adds useful context by enumerating what the listing contains and that credit cost is exposed, but it says nothing about the response shape, pagination, or whether the list is static or account-dependent.

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 short sentences, front-loaded with the verb and resource, with the provider enumeration parenthetical doing real informational work rather than padding. The parenthetical is slightly dense but each named provider earns its place by telling the agent what families of voices exist.

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 read-only listing tool with annotations covering safety and no output schema, the description supplies the essential context: what is listed, which providers, and that pricing is included. The only modest gap is that the agent does not know the exact shape of each voice entry or whether the list varies per account.

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 tool takes zero parameters, so there is no parameter meaning for the description to compensate for. The schema is trivially empty and nothing is left ambiguous about invocation.

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 ('List') and resource ('text-to-speech providers and preset voices') and names the concrete providers returned (Deepgram Aura-2, MiniMax HD, OmniVoice, Gemini 3.1 Flash) plus the credit cost field. This is clearly distinguishable from siblings like vivid_list_models or vivid_list_music_providers, which cover different resource domains.

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?

Explicitly tells the agent to call it before vivid_generate_voice, which is a real and actionable sequencing directive that picks out one sibling. It stops short of naming when-not-to-use or alternative discovery paths, but the intended workflow position is unambiguous.

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