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

With no annotations provided, the description carries the full behavioral burden and excels: it discloses async job semantics, the immediate return of id and credits_charged, terminal statuses (complete/error/canceled), downloads with direct URLs, and the per-character cost model with rounding. This is precisely the kind of operational context an agent needs and 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?

The description is front-loaded with the purpose sentence, followed by cost, then the async workflow, then file-input caveats — the right priority order. The bulleted MCP guidance keeps dense operational detail scannable, and every section earns its place; only the file-path paragraph is slightly wordy with its conditional clauses.

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?

For an async tool with nested objects, pricing implications, and an output schema, the description is remarkably complete: what it returns immediately, how to obtain the finished result, what terminal states look like, where downloads appear, and how to supply the input file correctly. Nothing an agent needs to drive this workflow end-to-end 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 description adds real value beyond it — especially for audio_file_path, where it gives a preference order (existing Magic Hour path or upload-URL file_path first, direct URLs only when stable and fetchable) plus the failure mode for hotlinks. The cost-per-character detail also links the pricing model to the prompt parameter, supplementing the schema's character-limit note.

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?

The opening sentence "Clone a voice from an audio sample and generate speech" states a specific verb and resource with no ambiguity. The cloning concept inherently distinguishes this tool from the sibling ai_voice_generator_create_audio, so an agent can tell them apart without opening either 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?

The MCP guidance explicitly tells the agent what to do after invocation: call wait_for_audio_project with the returned id, or poll the GET endpoint until a terminal status. It also provides conditional input guidance — prefer Magic Hour file paths, use the presigned upload flow when in doubt, and beware hotlinked URLs. However, it never explicitly contrasts this tool with ai_voice_generator_create_audio for the selection decision itself.

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