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

Annotations already establish this as a safe, idempotent read, and the description still adds substantial behavior: the exact call budget per range (15 sales pages + 10 class pages, doubled when comparing, capped at 51), a cached site lookup, and the partial-result rule where short totals are named and change is omitted. It also defines metric semantics that matter for interpretation (netSales is after discounts before tax; collected is payments received).

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?

Front-loaded with what the agent gets before any caveats, and every sentence carries information (metrics, siblings, metric definitions, partial behavior, cost). The style is telegraphic and the call-budget sentence packs three facts together, which slightly raises parsing effort.

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?

There is no output schema, and the description compensates by enumerating the returned metrics and defining the two ambiguous ones. Combined with the partial-result rule and the call budget for a fan-out tool with up to 51 calls, an agent has everything needed to call it and to set expectations about cost and completeness.

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 baseline is 3, but the description adds real cost semantics for compareToPrevious (the call budget doubles) and reinforces that range and startDate/endDate are mutually exclusive. The range presets themselves gain no new meaning beyond the enum descriptions.

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?

"How the studio did in one period" is immediately qualified by the exact metric list it returns: sale count, net sales, amount collected, average sale, unique clients, class fill. It explicitly scopes out siblings (sales_summary and class_attendance_summary handle breakdowns) and out of scope content (no line items, no class rows), so an agent can separate it from the other summary tools 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?

It names two concrete alternatives with the condition that selects them (breakdowns go to sales_summary and class_attendance_summary) and rules out line-item and class-row use. It does not address the other period-summary siblings such as membership_summary or new_clients_summary, so the routing is clear but not exhaustive.

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