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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds one genuinely useful behavioral fact — every voice supports 29 languages — but says nothing about whether the list is paginated, filtered, or how large it is.

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?

Two short sentences with no filler, and the useful attribute list comes first. The phrasing 'Voices add_voiceover can use' is slightly clipped and reads awkwardly, which keeps it from a 5.

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 should clarify what comes back — it lists voice attributes but not whether an identifier is returned, which an agent needs to pass into add_voiceover. For a simple read-only list tool the gaps are modest but real.

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?

There is a single optional projectId parameter at 100% schema description coverage, so the schema already explains it ('Project to act on (default: the open one)'). The description adds no meaning beyond that, which is the expected baseline when the schema does the work.

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 identifies the resource (voices) and ties it to the consumer tool add_voiceover, and lists the attributes each voice carries (name, gender, accent, style). The verb 'list' is only implied by the name/title rather than stated, so an agent infers the read operation rather than reading it.

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?

By naming add_voiceover as the consumer, it implies this is the lookup step before adding a voiceover. It never says explicitly 'call this before add_voiceover' nor excludes any other use, so the workflow guidance is inferred rather than stated.

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