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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false, so safety is covered and the trailing 'Read-only' is largely redundant. The description does add real value beyond the annotations by disclosing the state machine (generating | completed | failed) and the failure payload (human-readable error plus failureKind), which helps an agent interpret polling results.

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 tight sentences, front-loaded with the verb and purpose, followed by return semantics and a one-word safety note. No filler or repetition.

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 single-parameter polling tool with full annotations and an output schema, the description covers purpose, usage context, and the meaningful state values an agent needs. Nothing required to invoke or interpret it 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 100% and there is a single required parameter whose schema description already explains its origin ('The id returned by the speak tool'). The description adds only 'by id', so the baseline 3 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?

States a specific verb and resource ('Look up a VoiceLabs generation by id') plus the intended purpose ('to poll its status'), which clearly distinguishes it from siblings like speak (creates a generation) and list_captures. An agent can select this tool without ambiguity.

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 phrase 'to poll its status' establishes the context of use — checking on an asynchronously created generation — and the schema ties the id to the 'speak' tool. It does not explicitly state when not to use it or name alternatives, so it falls short of a 5.

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