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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds meaningful behavioral context by noting the daily aggregation and the bulk batch execution capability through customer_ids, which are not captured in annotations.

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 extremely concise, front-loading the primary purpose in the first sentence and the bulk support detail in the second. Every word adds value with no repetition or fluff.

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?

The description lists expected metrics and bulk support, giving a good sense of output contents, but without an output schema or further details on parameter semantics, date handling, or account selection, some ambiguity remains. It is adequate but not thorough for a four-parameter tool.

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 0%, so the description must compensate, but it only partially does. It clarifies that customer_ids enables batched execution and that days relates to the daily breakdown, but it leaves 'account' and 'customer_id' unexplained and does not clarify their relationship or which to use when.

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 provides a 'daily performance breakdown' with specific metrics (cost, impressions, clicks, conversions, revenue), making its core purpose obvious. It differentiates from sibling tools like google_ads_today or google_ads_campaigns by emphasizing daily aggregation, though it lacks an explicit action verb like 'retrieve' or 'list.'

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 implies the tool is for daily performance data and bulk execution via customer_ids, giving a basic sense of when to use it. However, it does not explicitly contrast with sibling tools such as google_ads_campaigns or google_ads_today, nor does it explain when one input should be preferred over another (account vs customer_id).

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