Usage, quota and key limits

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is clear. The description adds meaningful behavioral context by enumerating exactly what usage data is returned and framing the tool as a pre-batch stop-check. This goes beyond the annotations without contradicting them.

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?

Two sentences with no wasted words. The output contents are listed first, and the operational guidance is placed second. Every phrase earns its place and the description is easy to parse quickly.

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 zero parameters and no output schema, the description carries the full burden of explaining what the agent will get. It does so by listing all return categories: monthly quota and remaining amount, today's sends, key scopes, daily cap, and remaining allowance. It also gives the practical trigger for calling it, making the context complete for this simple read-only tool.

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 input schema is empty and the parameter count is zero, so parameter semantics are not applicable. The baseline for zero-parameter tools is 4, and the description appropriately adds no irrelevant 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 names a specific verb and resource: it returns monthly quota, remaining quota, today's sends, and key-specific scopes, daily cap, and allowance. This is distinct from the sibling tools, none of which focus on usage or quota. A model can immediately know what this tool does without opening a schema.

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 explicitly tells the agent when to use the tool: 'Read it before a batch to know whether to stop.' This is clear context for invocation. It does not mention when not to use it or compare it to alternatives, but the purpose is unique enough among siblings that this is only a minor gap.

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