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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered by structured data. The description adds useful content context by enumerating the returned fields (plan, audits used, allowance), but says nothing about auth requirements, rate limits, or freshness of the usage counters.

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 compact sentence with zero filler, and the most important content (the key's plan and usage) is front-loaded. Nothing could be removed without losing 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?

For a parameterless, read-only lookup with no output schema, the description adequately enumerates the returned fields so the agent knows what to expect. It stops short of noting whether usage is live or cached, which is a minor omission given the tool's simplicity.

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 takes zero parameters, which is the baseline-4 case; there is nothing for the description to disambiguate. The schema coverage is 100% and empty, so no compensating text is required.

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 names the specific resource and its contents — the key's plan, API audits used this month, and the monthly allowance — so an agent knows exactly what data comes back. It is a noun phrase rather than a verb+resource, and it does not explicitly differentiate itself from audit-oriented siblings like list_audits or get_audit, but the scope is unambiguous.

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 statement of when to call this tool versus the audit siblings, nor any prerequisite or trigger condition. An agent must infer from the name alone that this is a quota/plan lookup rather than an audit listing.

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