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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered and the closing 'Read-only' is largely redundant. The description does add useful metric semantics (POAS 1.0 = break-even, break-even ACoS) that go beyond annotations, but says nothing about pagination, truncation, or behavior when no ad platform is connected.

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?

A single dense sentence that front-loads the metric set and ends with the read-only note. It is efficient, though the long parenthetical-free run of metrics makes it slightly list-like rather than prioritized.

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 read-only analytics tool with a fully documented schema and explicit annotations, the description covers the metric meaning and breakdown options an agent needs. Missing only edge-case behavior (empty results, unconnected platforms), which is minor given the annotation and schema richness.

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%, so all seven parameters are already documented in the schema, including defaults and the platform/group_by value lists. The description echoes the grouping options and break-even ACoS but adds no syntax or interaction detail (e.g. how platform interacts with group_by) beyond the schema, so the baseline 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?

States a specific verb+resource (ad performance across connected ad platforms) and enumerates the exact metrics returned (spend, attributed sales, ACoS, ROAS, TACoS, POAS, blended POAS, contribution after ads) plus the supported breakdown dimensions. This clearly separates it from siblings like get_ad_health, get_ad_recommendations, and get_orders.

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?

The description implies usage via the date range and grouping options, but it never says when to choose this over get_ad_health or explain_ad_change, nor does it state prerequisites such as needing a connected ad platform. Usage is inferable but not explicit.

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