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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive, so safety is covered. The description earns credit by enumerating the response contents (used, limit, remaining, overage, run-rate projection, plan, raw-event retention), which is the behavioral detail an agent needs since no output schema exists. It doesn't state whether the run-rate projection is per-day/per-month or how overage is signalled, leaving a small gap.

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?

One sentence, front-loaded with the resource and scope, and the dash-delimited list of returned metrics is dense but every item earns its place. Slightly run-on, but no filler.

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 no output schema, the description correctly compensates by listing the returned fields, and the sole parameter is fully documented in the schema. Only the usage/routing guidance against sibling reporting tools is missing, which is a modest gap for a 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 single 'org' parameter has 100% schema description coverage, including the default-organization behavior and a pointer to list_organizations, so the schema carries the full burden. The description adds nothing about the parameter, which is the expected baseline here.

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?

States a specific resource and scope (the organization's event quota for the current billing period) plus the exact metrics returned, which is more than a restatement of 'Get usage'. It does not explicitly contrast itself with the closest sibling, event_stats, but the quota/billing framing is distinct enough to separate them.

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 versus event_stats or the other reporting tools, and no prerequisites or exclusions. The 'current billing period' phrase is scoping context, not usage guidance.

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