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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds non-obvious behavior: results are paginated with total/hasMore, and when filtering by language each voice returns only the matching language metadata — a subtle shaping of the response an agent could easily miss.

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?

Four tight sentences: capabilities first, then filtering, then pagination, then the downstream link. Zero filler; each sentence carries actionable content.

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 values need not be spelled out, yet the description still flags total/hasMore for pagination. With the two undocumented params covered through prose, nothing an agent needs in order 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?

Schema coverage is 50%: limit and offset are documented in schema, while query and language are bare. The description compensates by explaining that `query` matches text in name, tone, gender or nation and that `language` takes a code or locale with concrete examples, adding meaning well beyond the schema.

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?

Specific verb+resource ('List selectable narration voices') followed by an enumeration of returned fields (id, display name, tone, gender, nation, languages). It is clearly distinguishable from the mutation sibling set_voice, which it names explicitly.

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 concrete filter examples ('hu' or 'hu-HU') and tells the agent how to continue pagination with total/hasMore plus offset, and what to do with results ('Use the returned id with set_voice'). No explicit when-not-to-use case, but the guidance is well beyond implied usage.

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