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

Annotations already declare readOnly/openWorld/non-destructive, so the safety bar is low, yet the description adds genuine value: the output shape (volume, competition, bid estimates) and the important caveat that volume is bucketed by Google rather than exact. That bucketing note is the kind of trait annotations cannot convey.

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 compact clauses, front-loaded with the tool's identity and outputs, no filler. Every sentence carries information, though the final bucketing note could be folded in slightly tighter.

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?

No output schema exists, and the description compensates by naming what is returned. For a read-only ideation tool with non-required params this is close to sufficient, with only the customerId/limit and pagination behavior left unaddressed.

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 already documents pageUrl, keywords, languageId and geoTargetIds. The description adds the useful 'and/or' relationship between keywords and pageUrl, but says nothing about the undocumented customerId or limit parameters.

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 for seed keywords and/or a URL') and enumerates the returned metrics (volume, competition score, top-of-page bid estimates). This is clearly distinguishable from mutation siblings like add_keywords and update_keyword, though it never names a sibling explicitly.

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 phrase 'Works pre-spend' implies it can be used before a campaign exists, which is real context, but there is no explicit when-to-use guidance, no prerequisites (e.g. whether a customerId is required), and no alternatives named despite many sibling research/report tools.

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