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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), but the description adds genuinely non-obvious semantics: latest_payments is a run-rate from the most recent payment per customer, not lifetime turnover, and no lifetime figure exists because accrual is recorded per owner. That prevents a likely misinterpretation of the numbers. It stops short of describing the shape of the returned rollup or how many apps come back.

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 payload comes first (what the rollup contains, then sort order), followed by the run-rate caveat and then the routing sentence. Three dense sentences with 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 does the work of naming the returned metrics and ordering, and the run-rate caveat is essential context that is included. The only omission is the behavior of include_samples, which leaves one caller-facing decision unexplained.

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?

There is exactly one parameter, include_samples, with 0% schema description coverage, and the description never mentions it or what 'samples' would contain. The otherwise rich description does not compensate for that gap, so an agent must guess the effect of setting it.

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 verb+resource (per-app revenue rollup) and enumerates the metrics returned (latest_payments, refunded, MRR, paid customer count) plus the sort order. An agent can distinguish it from revenue_summary purely from the description.

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?

Explicitly says 'Use to compare products at a glance; use revenue_summary for one app in depth.' This names the alternative sibling and the condition that selects it, so nothing is left to inference.

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