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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The description adds real behavioral value beyond that: deterministic ordering ('newest first') and the fact that the response includes both voice ids and the set of providers the server can save from.

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?

A single sentence with no filler, front-loading the resource and scope, then ordering, then the actionable id, then the secondary provider list. Every clause carries information an agent would otherwise have to discover by calling the tool.

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 tool with full annotation coverage and an output schema, this is complete: what it lists, how it is ordered, what the key field is for, and what else the response contains. Nothing needed to invoke it 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 and the baseline of 4 applies. The sentence instead spends its words on the return payload, which is the only meaningful semantic surface here.

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 specific resource ('the voices this account saved from a provider'), its ordering ('newest first'), and its payload ('each with the id'), so an agent knows exactly what comes back. It does not explicitly contrast with the nearest siblings (save_voice, list_models), leaving a small ambiguity about saved vs. provider-catalog voices.

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?

Usage is implied rather than stated: 'the id to pass as generate_voiceover's voice' tells the agent this is the lookup step before a voiceover, which is a genuine workflow pointer. However, there is no explicit when-to-use/when-not statement and no mention of save_voice as the way voices get here, so the agent must infer the entry conditions.

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