Google 広告の実績を取得

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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description redundantly but consistently states 読み取り専用. Beyond that it adds genuinely valuable behavior: costMicros must be divided by 1,000,000 uniformly across currencies, conversions may be fractional, and int64 fields are serialized as strings under proto3 JSON rules. It stops short of disclosing limits, pagination, or whether large date ranges are truncated.

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?

Four compact sentences with zero filler, and the most important fact (what is returned and that it is read-only) is front-loaded before the unit-conversion caveats. Nothing is repeated from the schema or annotations.

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 carries the burden of explaining return values, and it does so for the trickiest cases: micros conversion, fractional conversions, and string-encoded int64s, plus the explicit note that CTR/CPC are not provided. It omits the shape of the result set (columns/rows), pagination, and row limits, which leaves a modest gap.

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 five parameters (including the level enum default and the customer_id fallback to GOOGLE_ADS_CUSTOMER_ID) are already documented. The description adds no parameter-level detail beyond the schema, so the baseline of 3 applies; its value-unit notes concern returned fields rather than inputs.

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 states a specific verb and resource (Google 広告の実績を取得) and enumerates the exact metrics returned (費用・表示・クリック・CV・CV 値), so an agent knows precisely what data comes back. It does not, however, differentiate itself from metric-bearing siblings such as google_ads_search or google_ads_keywords, leaving some ambiguity about which tool supplies report-style aggregates.

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?

No when-to-use or when-not-to-use guidance is given, and no sibling alternative is named. The closest thing to guidance is the instruction to compute CTR/CPC downstream, which is about post-processing, not about selecting this tool over google_ads_search.

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