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 by signaling that the list is current-state and time-sensitive ('now') and that availability is bounded per language, which affects how an agent should react to a missing language.

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 short sentences, front-loaded with the core action and followed by the returned fields, the availability constraint, and the hand-off to publish_board. No filler; every clause carries information an agent needs.

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 carries the burden of describing the return shape, and it does so explicitly: per-language voice list with id, name, gender, and default. Combined with the zero-parameter schema and existing annotations, nothing needed to call or interpret this tool 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 the baseline is 4 and nothing in the schema requires compensation. The description correctly implies the listing is site-scoped and unfiltered rather than describing any input options.

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 and resource ('Lists the voices this Notematics site can voice narration with now') and enumerates what each entry contains: id, name, gender, and the language's default voice. An agent knows exactly what this returns, and it is clearly distinct from the board-oriented siblings.

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 downstream workflow: pick a voice here and pass it to publish_board as narration_voice. It also states a real constraint ('A language that is not listed cannot be voiced now'), which tells the agent what to do when a target language is absent. No explicit exclusions or alternatives are named, but there are no real alternatives among the siblings.

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