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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds genuine behavioral context beyond that: the URL is short-lived, defaults to 30 minutes, the max is enforced server-side by Hub, and it must not be cached. It stops short of failure modes (e.g., what happens if the recording has no audio yet).

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 with no filler, front-loaded with the core action and followed by expiry semantics and the caching warning. Every sentence carries distinct 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 full parameter coverage, the description sufficiently explains what is returned (a signed download URL), its lifetime, and the auth requirement. The only notable omission is error/precondition behavior when audio is unavailable.

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 recordingId and expiryMinutes are already documented in the schema, and the description largely restates the 30-minute default. It only marginally adds value by noting the max expiry is enforced by Hub. Baseline 3 is appropriate when the schema does the heavy lifting.

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: generate a short-lived signed URL for a recording's audio, even noting typical formats (MP3/WAV). It is clear what the tool returns, but it never distinguishes itself from close siblings like hub_get_media_url or hub_get_preview_url, leaving the agent to infer which URL variant it wants.

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 gives a clear operational directive (do not cache, request fresh each time) and states the required recordings:read scope, which is real usage guidance. However, it never says when to prefer this over the sibling URL tools (media/preview), so the alternatives question is left unanswered.

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