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

The annotations already declare readOnlyHint=true and openWorldHint=false, so safety and side-effect behavior are covered. The description adds useful behavioral context by naming the three returned values, including per-window audio seconds remaining, though it does not elaborate on auth requirements or response formatting.

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?

The description is a single sentence with no filler and is front-loaded with the resource being described. Every element earns its place by naming the plan, allowance, and remaining quota.

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 simple zero-parameter, read-only usage endpoint, the description covers the essential return values and is sufficient for an agent to understand what it provides. It could be slightly more complete by clarifying the window length or response format, but no output schema exists and the current detail is adequate.

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?

The tool has zero parameters, so there are no parameter semantics to document. Schema coverage is trivially complete, and the description does not need to compensate for missing parameter details.

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 identifies a specific resource: the API key's plan, audio allowance per window, and remaining seconds. It is clear what information is retrieved, though it uses a noun phrase rather than an explicit verb and does not directly compare itself to the sibling tools.

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 description states what the tool returns but gives no guidance on when to call it, when not to call it, or how it relates to alternatives like speak or list_voices. Usage is only inferable from the tool name and return content.

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