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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds that the estimate is derived solely from duration, which usefully signals it is an approximation and not a quote, but it says nothing about precision, rounding, or whether per-workflow settings affect the figure.

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?

A single front-loaded sentence with no filler; every clause carries information. Slightly terse given the ambiguity around what the returned credits mean.

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?

An output schema exists, so return-value explanation is not required, and for a one-parameter calculator the description covers purpose plus units. The remaining gap is what the estimate is based on (quality tier, model) and how authoritative it is.

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 description must carry the unit — and it does by stating '(seconds)' next to duration. It adds nothing further: no guidance on fractional values, minimum duration, or whether the value must match an actual audio file's length.

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 specific verb ('Estimate') and resource ('credit cost of transcribing audio') and names the driving input (duration in seconds). That makes it clearly distinct from credit-balance or package-listing siblings, though it never explicitly names those siblings.

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?

There is no explicit when-to-use statement or named alternative, but the wording ('estimate cost ... of the given duration') strongly implies a pre-flight check before starting a transcription. The agent must infer that context rather than being told.

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