Account usage per hour

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

The annotations already establish that this is a read-only, idempotent, non-destructive operation. The description adds useful behavioral context beyond that: oldest-first ordering, exact returned metrics, UTC-day aggregation when granularity=day, and a warning that long hourly ranges produce many rows.

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 dense and front-loaded: it starts with the core resource and returned metrics, then adds scope constraints, use cases, granularity advice, and the row-volume warning. Every sentence contributes useful selection or invocation guidance without repetition.

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 appropriately explains what the tool returns, including the metric set and ordering. It also covers the key invocation constraints around date windows, granularity, and long-range row volume, so an agent has enough context to 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?

Schema coverage is 100%, so the schema already documents all three parameters, making the baseline 3. The description adds meaningful practical semantics by explaining that granularity=day rolls hourly rows into UTC days and that a date window should always be supplied.

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 states a specific resource and scope: account-wide hourly usage, with page views and several error metrics, and explicitly says it is not broken down by application. This distinguishes it from narrower siblings like errors_by_hour and page_views_by_hour, though it does not name those alternatives directly.

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?

It gives clear use cases such as checking plan usage, ignore-rule effects, and dropped over-quota errors, plus practical guidance to use granularity=day for long ranges and always pass a startDate/endDate window. It does not explicitly say when to choose this over the sibling hourly tools, so it stops short of full alternative routing.

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