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

Annotations already cover safety (readOnly, idempotent, non-destructive), so the bar is lower, and the description still adds real behavioral context: a Premium entitlement requirement, a nightly-rollup source that excludes today, and sparse output where only active days appear. The only substantive gap is that it doesn't say what happens on a non-Premium account (error vs. empty result).

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?

Two tight sentences with no filler; the payload contents are front-loaded and the caveats (rollup lag, sparse days) follow. It opens with a noun phrase rather than a verb, which is slightly less scannable but costs almost nothing.

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?

An output schema exists, so return structure need not be described, yet the description still supplies the interpretation an agent needs: data is one-day stale and missing rows mean no activity rather than an error. Together with the Premium gate and the day-range default, nothing required to call or interpret this tool is missing.

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 description coverage is 100% and the single 'days' parameter is fully documented with default 30 and max 90 in the schema. The description's 'up to the last ninety days, thirty by default' simply restates those bounds rather than adding format or interaction detail, so the baseline of 3 applies.

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 enumerates exactly what comes back — daily page views, approved supports, amounts, and the visitor-to-supporter conversion rate — so the resource is unambiguous. It never states a verb or contrasts itself with overlapping siblings such as get_dashboard_summary or get_wrapped, so an agent must infer the boundary itself.

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?

Usage is implied rather than stated: 'Part of Premium' signals an entitlement gate, and the rollup note tells the agent this is for historical, not real-time, numbers. There is no explicit when-to-use-this-instead guidance against the other analytics-flavored siblings, leaving routing to inference.

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