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

With no annotations, the description carries the full burden and does so well: discloses cost (15 credits), a per-account cap (max 10 clones), the return handle (clone.id), and non-obvious host-rendering behavior ('renders as an interactive panel... do NOT repeat its contents'). These are exactly the traits an agent cannot infer from the schema.

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?

Dense but front-loaded: purpose, legal/prereq constraint, quality guidance, cost/limits, return value, host-rendering rule. Every sentence earns its place with no filler.

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?

No output schema exists, yet the description explains the salient return value (clone.id) and its downstream use, plus the host-panel behavior. For a 3-param mutation tool, nothing an agent needs to call it correctly is missing.

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 67% and the schema already documents name and sampleUrl (including formats and the upload_file hint). The description adds input-quality guidance ('1–2 minutes of clean speech with no music or background noise') that the schema does not provide, though it leaves the optional description field unaddressed.

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 ('Create an instant voice clone from a speech recording') and names the provider. It is clearly distinguishable from siblings like delete_voice_clone, list_voices and change_voice.

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 explicit when-to-use constraints (only the user's own voice or one they have permission for), prerequisite routing ('use upload_file first'), and downstream routing (use clone.id as voice_id in create_voiceover, create_avatar_video, change_voice). This is near-complete routing guidance.

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