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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint=false), so the description's value is in the extras it adds: results are bounded, filtered by the tenant's plan, limited to active voices, and identified by opaque tenant-scoped handles rather than raw provider IDs. That is meaningful context an agent could not derive from the schema. Pagination behavior is left unstated despite the pageSize parameter, keeping it off a 5.

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?

One front-loaded sentence with no redundant restatement of the title. It is dense with qualifiers ('bounded', 'plan-filtered', 'tenant-scoped opaque') but every phrase carries information rather than padding.

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 explained, but for a paginated listing tool the description omits how paging works (whether pageSize alone is sufficient or a cursor/next-token is returned) and how a caller should proceed from returned handles to synthesize_speech. Adequate but with clear gaps for a discovery tool.

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 description coverage is 0% and the description mentions none of the three parameters — the language filter, the provider enum, or pageSize. The names are largely self-explanatory and the enum is in the schema, but 'plan-filtered' is the only filtering concept the description surfaces, so it does not compensate for the coverage gap.

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 (Lists) and resource (text-to-speech voices) with useful qualifiers: 'bounded, plan-filtered', 'active', 'tenant-scoped'. This distinguishes it from synthesize_speech, get_tts_audio, and list_tts_syntheses, which are about synthesis/audio retrieval rather than voice discovery.

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 only implied — an agent can infer this is the lookup step before calling synthesize_speech, but the description never says so explicitly. It also does not state when not to use it versus list_tts_syntheses or get_tts_audio, and gives no prerequisite context about plan eligibility beyond the adjective 'plan-filtered'.

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