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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description goes beyond them with genuinely useful behavior: costs are in account currency converted from micros, and the range defaults to the last 30 days. It stops short of describing aggregation granularity or return shape.

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 that front-load the returned metrics and append the currency/default-window caveats. No filler, every clause carries information.

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 metric list usefully compensates for the missing return documentation, and the zero-required-parameter design is partly addressed by the default-range note. It still omits customerId resolution, aggregation granularity (per campaign per day vs. aggregate), and any pagination or result-size limits.

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 67%, and the description reinforces the date semantics (last-30-day default) rather than extending them. The undocumented customerId parameter gets no explanation in either place, and no date-format or requiredness detail is added beyond the schema's own notes.

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 names a specific verb+resource and enumerates the exact metrics returned (impressions, clicks, cost, conversions, CTR, avg CPC), which is more than a tautology. It does not, however, differentiate itself from near-siblings like get_ad_performance or get_campaigns, leaving the agent to infer the distinction.

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 only usage signal is the default window (last 30 days). There is no statement of when to choose this over get_ad_performance, get_campaigns, or run_report, and no prerequisites or exclusions are given.

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