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

Annotations already flag a destructive, non-idempotent, open-world write, and the description goes well beyond them: an explicit cost (SPENDS 5 credits), mandatory consent attestation with a 'never attest on your own' warning, rate limits (3 new per 24 h) and plan caps (Starter 2 / Pro 5 / Scale 15). These are exactly the irreversible-cost and authorization facts an agent needs before calling.

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?

Front-loads the purpose, then cost, then the consent gate, then limits, in descending order of importance. The parentheticals are dense but every clause carries actionable constraint information; nothing is redundant with the schema or annotations.

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 a nested-object, 6-parameter, no-output-schema mutation, the description supplies the consent sequence, cost, plan/rate limits, and sample constraints an agent needs to invoke it correctly. The only undetailed element, exact return shape, is implied by the stated voiceId usage.

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?

With only 50% schema coverage, the description compensates heavily for the key samples parameter: count (1-25), size cap (≤10 MB each), accepted sources (r2Key from create_upload/import_asset_from_url or direct https URL), and quality guidance (1-3 minutes of clean speech). It leaves name, description, languageCode and removeBackgroundNoise unexplained, but those are largely self-describing.

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?

Names a specific verb (Create) and resource (instant voice clone / ElevenLabs IVC), making it trivially distinguishable from sibling creation tools like create_character or create_influencer. The scope (this account only) and downstream consumer (generate_speech voiceId) further pin down what it produces.

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?

Provides an explicit prerequisite workflow (call get_voice_consent_statement first, show it, only proceed after in-conversation confirmation), states a hard exclusion (not on the Agent plan), and routes sample acquisition to create_upload / import_asset_from_url. It even names the downstream tool for using the result, so alternatives and conditions are fully covered.

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