Ad group performance

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safe read-only nature is covered. The description adds some scoping behavior (date range, campaign filter, segmentation) but does not disclose return-value details, default date-range behavior, or any edge cases. No contradiction with 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?

A single, front-loaded sentence conveys the core scope and optionality without filler. Every phrase adds value and the description is appropriately compact for a straightforward reporting tool.

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 8 optional parameters and no output schema, the description gives enough to understand what the tool does and when to pick it, but it omits what specific metrics are returned and how date_range interacts with custom start/end dates. Schema descriptions and annotations compensate partially, making this minimally viable.

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 75%, with most parameters already documented in the input schema. The description lightly reinforces date range, campaign filtering, and segmentation but does not add meaningful detail beyond the schema. Baseline 3 is appropriate here.

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 names the exact resource level (ad groups), the nature of the data (metrics), and the scoping options (date range, campaign filter, segmentation). This distinguishes it clearly from sibling report tools like campaign_performance, keyword_performance, and geo_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 makes the primary use case clear: retrieving per-ad-group metrics, with optional campaign filtering and segmentation. However, it does not explicitly contrast with alternatives such as campaign_performance or keyword_performance, nor does it state when not to use this tool.

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