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

Annotations declare readOnlyHint, idempotentHint, non-destructive, openWorld. The description adds the default date range and interpretation guidance, but does not disclose pagination, rate limits, cost-unit conventions, or what happens across time zones. Given annotations cover safety, a 3 is fair.

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 short, front-loaded fragments with no filler. Slightly telegraphic, but every sentence carries 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?

With 5 parameters at 20% schema coverage and no output schema, the description should explain the undocumented parameters and return shape. It supplies only a metrics list and a default window, which is insufficient for correct invocation.

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 only 20% – only the required 'property' parameter is documented. The description mentions no parameters beyond implying a date range ('last 30 days'), leaving limit, campaign, startDate, endDate, and their formats/behaviors undocumented.

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?

Names the resource (responsive search ads) and the metrics it returns (ad strength, final URL, headlines count, CTR, cost, conversions). It is distinguishable from siblings like ads_keyword_performance or ads_campaign_performance, though it doesn't explicitly contrast with them.

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?

Provides a default time window (last 30 days) and an interpretive hint ('low ad strength and low CTR ads are rewrite candidates'), implying diagnostic use. However, it does not state when to use this tool versus ads_recommendations or other performance tools.

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