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

Beyond readOnlyHint=true and openWorldHint=false, the description adds a genuinely useful behavioral trait: the returned WAV link is short-lived, telling the agent to consume it promptly rather than store it. It also bounds the operation to a single string, which sets cost/latency expectations. It does not mention voice availability failures or locale fallback, so it stops short of 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?

Two short sentences with zero redundancy: the action and its output first, then the usage constraint. Nothing needs to be read twice and nothing is 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 and annotations cover safety, so the description only had to supply intent plus the ephemeral-link caveat, which it does. The residual gap is the absence of any pointer to preview_voice for the adjacent case, which a low-complexity two-parameter tool can mostly survive without.

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 100%: 'ipa' is documented as 'exactly as it would be saved' and 'locale' as the BCP-47 voice selector, both richer than anything in the description. The only added semantics is the one-string-per-call cardinality, which is worth something but is the baseline expectation when the schema already 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?

Specific verb+resource: it speaks one IPA string and returns a short-lived WAV link for auditioning before saving. That distinguishes it from mutation siblings like save_dictionary_entry, but it never names preview_voice, the closest sibling, so the agent must infer the split (voice sample vs. IPA string) on its own.

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?

'One string per call, and only one the user asked to hear' gives a real constraint on how much to preview, implicitly discouraging bulk calls. However, there is no explicit statement of when to reach for this instead of preview_voice or suggest_pronunciations, so the routing decision is left to inference.

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