Keyword ideas (Keyword Planner)

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

With readOnlyHint=true and openWorldHint=true already declaring the safety profile, the description adds genuinely useful context beyond the annotations: the Google Ads developer-token access requirement that gates real volume data. It does not mention quota/rate-limit behavior typical of Keyword Planner calls.

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 with no filler: the capability and return payload come first, then differentiation, then the access prerequisite. Every sentence carries distinct 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?

There is no output schema, so the description correctly enumerates the returned metrics, and it also states the access prerequisite. For a read-only, open-world lookup tool, an agent has everything needed to call it correctly.

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%, so the schema documents url, language, countries and customerId. The description only echoes the seed-keywords/URL input concept and adds no syntax or constraints for the undocumented 'keywords' and 'limit' parameters, so it does not compensate for the gap. Baseline 3 is appropriate.

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 (Keyword Planner ideas from seed keywords and/or a page URL) and enumerates the returned metrics (avg monthly searches, 12-month trend, competition, top-of-page bid range). It also distinguishes itself from the sibling search_analytics by noting it surfaces demand for topics the site does not yet rank for.

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?

Gives clear context for use — seeding from keywords or a URL to find unranked topic demand — and names the prerequisite (developer token with Basic access). It does not, however, route the agent between this tool and its close sibling ads_keyword_volume, which is the most likely confusion.

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