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

With only openWorldHint=false and destructiveHint=false in annotations, the description adds meaningful behavior: it explicitly says the aggregation happens at read time and creates no new storage. That is useful context beyond the annotations, though it does not cover permission or freshness details.

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 two short sentences, with all information front-loaded. It wastes no words and packs the source, operation, output dimensions, and storage behavior into a compact form.

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?

For a tool with an output schema and three self-naming parameters, the description covers the key details: data source, grouping, metrics, and side-effect-free behavior. It is slightly incomplete only because it does not address parameter roles or when to prefer this tool over its close siblings.

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 description does not explain how companyId, periodStart, or periodEnd affect the aggregation. The parameter names and date patterns are self-explanatory, but the description adds no semantic detail such as inclusivity, defaults, or how the period maps to the monthly grouping.

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 states a specific operation (unions four ad platforms' daily tables at read time) and a concrete result (per-provider/month/currency spend/impressions/clicks/conversions plus CPA), which clearly identifies what the tool does. It does not explicitly name a sibling alternative, but the four-platform aggregation is enough to set it apart from the per-platform campaign-window tools.

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?

No guidance is given on when to choose this tool over ads_insight_summarize_campaign_window or the per-platform metric tools. The read-time/no-storage note implies a safe aggregation use case, but it does not state prerequisites, exclusions, or alternatives.

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