google_ads_compare_periods

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

No annotations are provided, so the description carries full burden for behavioral disclosure. It implies a read-only operation (performance comparison) but does not explicitly state safety, permissions, or side effects. The lack of behavioral context is a significant gap.

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?

The description is concise, with a clear one-liner purpose and an example that demonstrates usage. It avoids unnecessary details and is front-loaded with the main action.

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?

Given that an output schema exists, the description does not need to detail return values. However, it could mention what metrics are compared (e.g., clicks, impressions) or provide more context about the comparison scope. The example helps but the description is somewhat minimal for a tool with 5 required parameters.

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?

The description adds value beyond the input schema by specifying format requirements (YYYY-MM-DD) and clarifying that customer_id should be without hyphens. However, it only covers the 5 parameters with brief notes; schema coverage is 0%, so the description partially compensates but could be more detailed (e.g., allowed date ranges).

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 clearly states the tool compares performance between two time periods. However, it does not explicitly distinguish from sibling tools like google_ads_campaign_comparison or google_ads_compare_ad_performance, which are similar in nature.

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 description provides no guidance on when to use this tool versus alternatives. It simply describes the function without indicating context or exclusions, leaving the agent uninformed about selection criteria.

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