listVoices

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

With no annotations provided, the description carries the behavioral burden. It discloses the return shape ({ edge: [...], kokoro: [...] }) and the practical implication that voice IDs from either provider are usable. For a zero-parameter, read-only listing tool, this is sufficient transparency; only minor gaps like empty-list behavior or item shape remain.

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 tightly packed sentences with no filler. The main action and scope come first, followed by the return structure and usage guidance. Every sentence earns its place.

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 list operation with no output schema, the description is complete: it states what is returned, from which providers, and how to use the result. No essential calling information is missing.

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 input schema has no parameters, so the baseline is 4. The description does not need to clarify parameter meanings since none exist. It adds helpful context about the returned voice ids being usable, which complements the empty schema.

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 uses a specific verb ('List') with a clear resource ('available TTS voices across providers'). It explicitly contrasts with narrower sibling tools like listEdgeVoices by showing it returns both edge and kokoro voices, making the tool's scope unambiguous.

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?

The description clearly indicates this is the place to retrieve voice IDs for either provider and that these IDs can then be used elsewhere. It does not explicitly name alternatives or state when not to use this tool, but the 'across providers' framing plus the listEdgeVoices sibling implies the distinction.

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