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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuinely new context: 'Free' (cost), and the fact that results include account-scoped cloned voices and not just a generic roster. No pagination or return-shape detail, but the bar is lower given 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?

Extremely tight and front-loaded: cost note first, then scope, then the integration hint. Every clause carries distinct information with no filler.

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 no-parameter list tool with annotations covering safety and no output schema, the description supplies enough to call it correctly, and the 'ids usable as...' clause partially anticipates the return shape. It could say a bit more about what the returned entries look like, but nothing critical 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?

Zero parameters, so the baseline is 4; schema coverage is 100% and there is nothing further for the description to clarify.

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 names the resource concretely ('the speech roster plus the account's cloned voices'), which separates it from sibling lists like list_characters, list_flows, and list_models. The verb is only implied via the tool name, but the scope is 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?

It clearly states the downstream use case — the ids are 'usable as generate_speech's voice' — which tells an agent when this tool matters. It stops short of any when-not guidance or comparison to other listing tools.

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