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

The annotations already establish readOnlyHint, idempotentHint, and non-destructive semantics, so the description's 'Read-only' line is largely redundant. Its real added value is disclosing the empty-account behavior and the `emptyState` payload, a trait not derivable from the annotations or schema.

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, front-loaded with the operation and scope before the empty-state caveat. The standalone 'Read-only' sentence is redundant with readOnlyHint=true and is the only real waste.

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?

An output schema exists, so return fields need not be re-explained, yet the description still covers the one non-obvious outcome (emptyState on a fresh account). Nothing an agent needs to call this correctly 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 tool takes zero parameters, so there is nothing for the description to disambiguate — baseline 4 applies. The schema already closes the object with additionalProperties: false.

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 (the user's VoiceLabs voice profiles), and enumerates what is returned — cloned voices, presets, language, engine, usage counts. It is clearly distinguishable from write-oriented siblings like clone_voice_profile, but it never explicitly names or contrasts an alternative tool.

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 a concrete usage directive for the empty case: an empty list is normal on a new account, and the `emptyState` should be relayed rather than reported as a failure. It does not, however, say when to prefer this over ensure_voice_profile or clone_voice_profile.

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