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

Annotations already declare readOnly/idempotent/non-destructive, so the description wisely spends its words elsewhere: the URL is 'short-lived' (an expiry trait the agent cannot get from annotations) and 'private'/'tenant-owned' (an access-scoping trait). It does not say what happens if the synthesis is not yet complete, which is the main omitted behavior.

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?

One sentence, front-loaded with the return value, every clause informative (short-lived, private, completed, tenant-owned). No filler.

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?

The output schema means return shape needn't be explained, and annotations cover the safety profile, so the definition is close to adequate. Still missing the failure mode for an incomplete/failed synthesis and any sense of how short-lived the URL is, both of which affect agent retry strategy.

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 0%, so the single synthesisId parameter carries no documentation in either place; the description only implies it must identify a finished synthesis. The schema's regex pattern at least constrains format, keeping this at a baseline-3 rather than lower.

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: returns a download URL for a completed TTS synthesis, which is distinct from synthesize_speech (creates it) and list_tts_syntheses (enumerates them). The 'completed' qualifier implicitly separates it from a creation tool, though no sibling is named explicitly.

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?

'Completed ... synthesis' implies it should be called after synthesis finishes, but it never names the alternatives (get_job_status, list_tts_syntheses) or states the precondition explicitly. An agent must infer when this tool applies versus polling job status.

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