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

Annotations already cover the read-only, idempotent, closed-world safety profile, so the description is free to add real behavioral context: the default window is the last 30 days, from/to must be sent together and never after today, and byWeekday carries a days-held count so short spans mislead. What is missing is any sense of how the series is returned (row count, ordering, empty-day handling), which matters for a daily series.

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?

Scope and the key field distinctions are front-loaded, but the prose is dense and runs together several ideas in long sentences, including prescriptive narration rules ('quote it, never work it out') that are more policy than tool description. It could be shortened considerably without losing selection signal.

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 two-parameter, annotation-covered tool with no output schema, the definition covers scope, default window, field semantics, and sibling routing. The main gap is return-shape detail for the daily series, which the absence of an output schema leaves on the description.

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 both date parameters are already documented, but the description adds the consequence the schema only hints at: omitting them silently reads the last 30 days, so an operator-specified month or date pair must be forwarded explicitly. That is genuine meaning beyond the schema rather than a restatement.

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 opening sentence names the specific resource and granularity: daily revenue and spend over the current period. It then names the concrete fields (byWeekday, platformRevenueByChannel, revenueByChannel, spend) and clarifies that these are distinct per-day series rather than period totals, which separates it from get_summary and get_channels.

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?

Explicit when-to-use triggers are given ('when something changed', 'a trend or spike', 'one channel on a given day'), and the alternatives are named with their conditions: get_summary for whole-period totals across channels, get_channels for per-channel totals. It also states a hard routing rule — a named month, week, or two dates from the operator must be passed here.

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