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

Annotations carry only a title, so the description does the heavy lifting and delivers real behavioral facts: a 5-minute cap on source audio, per-second-of-source billing, and the fact that it returns a placeholder whose inline preview updates itself (i.e. async completion). It omits failure modes and any permission/account requirements, which keeps it short of a 5.

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-loaded with what the tool is, followed by required inputs, limits, pricing then return behavior — a sensible order with no filler sentences. The parenthetical tool-reference chain is dense enough to slow a first read, but every clause carries information.

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 and only a title in annotations, the description steps in to explain the return value (placeholder plus self-updating preview) and the key operational limits. Complete enough to invoke correctly; only failure/async-polling guidance is thin.

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 genuine provenance beyond the schema: source_audio_url must be a var2/https URL originating from recording, upload, or a previous result, and duration_seconds is a value the recorder reports. That provenance is not in the schema text and prevents a common misuse.

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 ('re-speak a recorded/uploaded voice in another voice') and immediately disambiguates against text-to-speech siblings by noting it keeps words, timing and emotion. The parenthetical aliases ('voice changer, ElevenLabs speech-to-speech') remove any doubt about which sibling (var2_create_audio) it is not.

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?

Names the concrete prerequisites and, crucially, where each input comes from: source_audio_url from var2_record_voice or var2_upload_asset, voice_id from var2_get_voice_list. It gives clear context for when this tool applies but never explicitly rules out alternatives (e.g. 'for text input use var2_create_audio'), so it stops short of full when/when-not guidance.

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