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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds useful context about the specific data returned (monthly usage, limits, reset), which goes beyond the annotations but does not disclose additional behavioral traits such as authentication or rate limiting. It is adequate but not extensive.

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, well-structured sentence that immediately states what the tool returns. It is concise, front-loaded, and contains no filler or redundancy.

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 tool with no parameters and no output schema, the description is sufficient. It clearly enumerates the key data points (requests used, plan limit, per-minute limit, reset time). The absence of details on response format is acceptable given the simplicity and the lack of an output schema. It is complete enough for an agent to understand the tool's purpose and call it correctly.

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 the description does not need to elaborate on parameter semantics. With no parameters, the baseline is 4, and the description is consistent with that. It doesn't add extra parameter info because none exists.

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 clearly states the tool's function: it returns usage metrics for the calling account (requests used, plan limit, per-minute limit, and reset time). This is specific and distinguishes it from the many other get_* tools, none of which cover usage.

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 implies this is for checking API usage, but it does not explicitly state when to use it or mention any alternatives. Since there are no sibling tools with similar functionality, the lack of exclusion is not a major issue, but there is no direct guidance on the intended context.

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