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

Far beyond the annotations, it discloses cost_micros to cost conversion with currency_code and currency_minor_unit_digits, what happens when currency is unknown, row_limit being a response cap rather than Google's page size, truncation and partial_collection signals, next_page_token only being safe sometimes, a five-value data_availability vocabulary with correct interpretations of no_rows and access_error, and a prompt-injection warning on returned strings. It also discloses side effects the annotations only hint at (token consumption, an XBOSS task being created and stored). The one flaw is internal tension: it first says '읽기만 합니다' (read only) and later says the call is 'not purely read-only', which could leave an agent unsure about side effects even though the later statement matches readOnlyHint=false.

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 purpose is front-loaded and the paragraph ordering is logical, but the text is bloated: 'metrics.impressions 는 metrics.impressions 로, metrics.clicks 는 metrics.clicks 로' is tautological filler, and the idempotency block is generic boilerplate that even references unrelated 'anonymous taste calls'. The trailing sentences about XBOSS task creation repeat themselves and partially retract the earlier read-only claim, so length is not buying clarity here.

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 tool with nine parameters, no output schema and real complexity (pagination, currency conversion, partial availability), the description covers dates, currency, cost conversion, truncation, token continuation and data_availability states. The notable remaining gap is that, with no output schema, it never says how each row identifies which of the four campaign types it belongs to — the single most important thing for a combined-channels report — nor what dimensions do to row shape.

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 the baseline is 3. The description does add real meaning on top of the schema for several parameters: row_limit is the rows this call returns rather than the limit sent to Google, page_token is fed from a previous call's next_page_token, start/end dates are inclusive and follow the ad account timezone, and requesting metrics.cost_micros also yields metrics.cost. However it adds nothing about dimensions, which is the parameter that most shapes the result, and the metric-to-output mapping sentences mostly restate the field names.

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 states a specific verb and resource: aggregate performance for four named campaign types (Search, Display, Performance Max, Demand Gen) from a single Google Ads account in one call. It immediately bounds scope by excluding video campaigns and names the sibling tool to use instead, so an agent can distinguish it from google__ads__video__report without opening any schema.

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?

It gives a clear when-to-use ('combine four campaign types in one call over a period') and an explicit when-not with the alternative ('video campaigns are not included, use the video performance tool'). It also tells the agent how to react to no_rows ('widen the period and call again'). What it does not say is when to prefer the single-channel siblings (search/display/pmax/demand_gen reports) over this combined call, leaving that choice to inference.

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