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

Annotations already cover the read-only, idempotent, non-destructive nature, so the description appropriately adds behavioral context beyond them: the default current-month date window, per-campaign output breakdown, _summary inclusion, and batched execution support. It stops short of describing response formatting or potential API-side limits, but the important behavior is conveyed.

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 short and front-loaded: the first line names the core computation and default, the second captures output structure, and the third adds batching semantics. There is no wasted prose except very minor redundancy in 'bulk support' and 'bulk execution,' but it is still concise and scannable.

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 no output schema and an otherwise bare parameter schema, the description should clarify singular vs. plural account identifiers and when to use them; it does not. It delivers enough high-level meaning for selecting the tool, but invoking it correctly for a single account may still be ambiguous between account, customer_id, and customer_ids.

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%, and the input schema provides only bare parameter names. The description adds just a little semantics by mentioning date-range and customer_ids for bulk, but leaves since, until, account, and customer_id unexplained. Given the low schema coverage, the description does not compensate enough for five 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?

The description clearly identifies the resource (ROAS) and scope (a date range, defaulting to current month), and enumerates the returned data dimensions: per-campaign cost, conversions, revenue, and _summary. It lacks an explicit verb like 'returns' or 'fetches,' and it does not directly contrast itself with sibling tools such as google_ads_performance, but the purpose is still clear.

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 useful context: date range default and bulk support via customer_ids, implying when the tool should be used. However, it does not explicitly mention when to avoid it or which alternatives to use, such as google_ads_performance or google_ads_today, so the usage guidance remains implied rather than explicit.

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