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

Annotations already declare readOnlyHint=false, idempotentHint=false, openWorldHint=true. The description adds genuinely new operational context: cost ('Free'), latency ('long text takes over a minute'), and the exact return payload (MP3 link and length), which the annotation set does not convey.

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 clauses, front-loaded with the core action and return value, then dependency, then cost/latency caveat. No sentence is filler; the endpoint is appended compactly at the end.

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 correctly fills the gap by naming the return values, and it covers cost, latency, endpoint, and voice sourcing. What remains unstated is whether the call is synchronous or task-based and how the 'email' multi-account case behaves, both of which matter for an openWorld, non-idempotent 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 coverage is 100%, so the schema already documents all five parameters, establishing a baseline of 3. The description adds meaning the schema lacks: practical length guidance for 'text' (the schema has no maxLength) and the provenance of speakerId from kling_list_tts_voices.

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 ('Read text aloud with a Kling voice'), names the return artifact (MP3 link + length), and points to kling_list_tts_voices as the source of speakerId, which cleanly separates it from that sibling list tool and from kling_add_sound.

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 clear prerequisite path (speakerId comes from kling_list_tts_voices) and a practical usage constraint ('keep it to a few sentences'). It does not state explicit when-not conditions or contrast against siblings like kling_add_sound, so it falls short of a 5.

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