Campaign performance

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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds useful behavioral context beyond the annotations: the exact metric set, segmentation options, and the fact that money is in account currency units.

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?

Two concise sentences: the first front-loads the core function and metric list, the second summarizes segmentation and currency. No filler or redundancy.

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, the description appropriately enumerates returned metrics and explains the segmentation behavior. It does not describe row identity fields or default date-range behavior, but those are either implied by 'per-campaign' or covered in the input schema. The description is adequate for an agent to form a correct mental model.

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 88%, so the schema already documents most parameter meanings. The description reinforces the concept behind the 'segment' parameter and clarifies the output metrics, but it does not add per-parameter detail absent from the schema. Baseline 3 is appropriate.

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 that this returns per-campaign metrics for a date range and enumerates the specific metrics reported. It lacks an explicit operative verb like 'retrieves' or 'returns', but the resource and scope are clear and the metrics list distinguishes it from sibling reporting tools such as ad_group_performance and keyword_performance.

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 clear context: this is the tool for campaign-level performance metrics with optional segmentation. It does not explicitly state when not to use it or name alternatives, but the per-campaign scope and metric list make the intended use obvious relative to the sibling tools.

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