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

Annotations already cover the safety profile (readOnlyHint=false, openWorldHint=true, idempotentHint=false). The description adds genuinely useful behavior beyond that: Kling cleans the clip, the return is a voice id, the result is account-bound ('use it with the same email'), and cost is usually free — a cost signal no annotation carries.

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?

Roughly 50 words, front-loaded with the verb and resource, and every clause carries information. The trailing 'POST /videos/voices' is marginal value for an agent invoking by tool name, and '(voice_N)' is slightly cryptic, keeping 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 correctly states what comes back (the voice id) and how to use it. It covers source constraints, cost, and account coupling. It omits failure modes (bad URL, clip too short) and any rate/limit detail, which is a modest gap for a network-dependent write.

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 baseline is 3, but the description adds constraint detail the schema lacks (the 4.5-30 s duration window and 'clean speech' quality requirement) and ties the email parameter to a consequence ('use it with the same email'), which explains why the optional email matters.

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+resource ('Save your own voice') plus the exact downstream consumer (kling_omni_video v4, voice_N) and the source format (public URL of a clean speech sample). This distinguishes it cleanly from siblings like kling_list_voices, kling_delete_voice, and kling_list_tts_voices — an agent can route without opening any schema.

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 clear conditions for use: a public URL speech sample, 4.5-30 s, clean speech, and tells the agent to reuse the voice with the same email. It never explicitly names an alternative (e.g. kling_list_voices / kling_list_tts_voices) or a when-not-to-use case, so it stops 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.