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

Annotations already declare idempotentHint=true and destructiveHint=false, so the safety profile is covered, but the description adds real value on top: the exact idempotent contract ('returns the same profile with `created: false` and creates nothing') and the boundary that it cannot clone a real person's voice. It stops short of describing error behavior beyond that, but this is well above the annotation baseline.

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?

Three front-loaded sentences with no filler; the creation semantics come first, then the usage triggers, then the sibling exclusion. It is dense but every clause carries information, so it is efficient rather than padded.

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 5 parameters, an output schema, and full annotation coverage, the description supplies exactly what the structured fields cannot: the idempotency contract, the failure triggers that prompt calling it, and the hand-off to speak. An agent has everything needed to call it correctly.

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 description coverage is 100%, with enum values, defaults, and the exact-match/case-sensitivity rule all documented in the schema itself. The description adds only the informal notion of 'the given name' and 'the returned id', so the baseline 3 for a fully documented schema is appropriate.

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 description uses a precise verb and resource ('Make sure a voice profile with the given name exists on the user's VoiceLabs account, creating it from one of VoiceLabs' built-in (preset) voices if it does not') and explicitly distinguishes itself from clone_voice_profile, which a sibling tool. An agent can route to it without opening the 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?

It names the trigger conditions ('when list_voice_profiles comes back empty, or when speak reports NOT_FOUND for a voice'), tells the agent what to do next ('pass the returned id to speak'), and identifies the alternative it is not (clone_voice_profile, which needs the voice:clone scope and a recording). Nothing is left to inference.

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