キーワードの検索ボリュームと入札単価を調査

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

Annotations already declare readOnlyHint, destructiveHint, and openWorldHint, so the safety profile is covered and the redundant '読み取り専用' adds nothing. However, the description discloses two genuinely useful behavioral facts beyond the annotations: bid amounts are in micro units (1,000,000 = 1 currency unit) and related keyword suggestions are also returned.

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?

Three tight sentences, front-loaded with the primary purpose followed by the micro-unit caveat and the return content. Only the bolded '読み取り専用' is wasted space since it duplicates the readOnlyHint annotation.

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 correctly names the returned fields (volume, competition, bid range, related keywords) and flags the micro-unit format. Combined with the safety annotations and fully covered schema, an agent has enough to call it correctly; only rate-limit or auth context is absent, which is minor here.

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 four parameters (keywords, customer_id, language_id, geo_target_ids) are already fully documented with examples in the schema. The description adds no parameter-level syntax or constraints beyond that, 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 and resource: retrieve monthly average search volume, competition, and bid range for keywords via Keyword Planner. This is clearly distinct from the mutation-oriented sibling google_ads_add_keywords, so an agent can route correctly without opening either 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?

The retrieval purpose implies when to reach for this tool (researching keyword metrics before bidding), but there is no explicit when-to-use, no exclusions, and no named alternative — notably the easy-to-confuse google_ads_add_keywords is never mentioned. Usage is inferred rather than stated.

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