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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds value beyond that with pricing semantics (basic 5 credits/min, standard 12), the keyless/free call model, and the purpose of sampleUrl for auditioning before choosing.

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?

Three dense sentences: cost/free access first, then the catalog fields, then filtering and downstream use. Nothing is repeated from the schema and every clause adds information.

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?

With no output schema, the description fully documents the return shape, and it also covers the default-voice behavior and pricing relevant to choosing a voice. Nothing an agent needs to select or call this tool 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?

Schema coverage is 0%, so the description must carry the parameter burden, and it does: language is specified as ISO 639-1, and the tier enum values are qualified with their credit cost. Only the absence of examples or default-filter behavior keeps it from a 5.

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 a specific resource (the dub voice catalog) and enumerates the exact fields returned (id, language, tier, provider, gender, default, creditsPerMinute, sampleUrl), which cleanly separates it from siblings like list_presets or list_custom_presets. An agent knows precisely what it gets back before calling.

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 gives concrete downstream guidance: 'Pass an id as voice to dub or plan; omit voice for the default,' and states the tool is free and keyless. It doesn't explicitly name a contrasting sibling it should be preferred over, which keeps it short of a 5.

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