get_keyword_performance

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds modest behavioral context beyond that: the default 100-row cap and the accepted date-range formats. It says nothing about which metric fields are returned, whether results are truncated silently, or what happens when the ad group has no data.

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 one-line purpose statement is front-loaded, and the Args block is compact and scannable. Given 0% schema coverage the per-parameter lines earn their place rather than repeating documented schema text, though the 'Args:' format is a leftover docstring convention rather than prose tailored to an agent.

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?

There is no output schema, so the description must explain what comes back — yet it names no metrics (impressions, clicks, cost, conversions, CTR, etc.) and gives no indication of result shape or ordering. For a reporting tool with four parameters, no annotations on return behavior, and no output schema, that is a substantial omission an agent cannot fill from structured fields.

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 property titles are bare ('Customer Id', 'Date Range'), so the Args block carries real weight here, clarifying that customer_id is a Google Ads customer ID and that date_range accepts a predefined value or 'YYYY-MM-DD,YYYY-MM-DD'. The gap is that no predefined values are enumerated beyond the schema default of LAST_30_DAYS.

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 verb and resource with scope: 'Get keyword performance metrics for an ad group.' An agent immediately knows it returns keyword-level metrics scoped to one ad group. It does not, however, distinguish itself from the sibling get_keyword_performance_report, whose name suggests an overlapping purpose.

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?

There is no when-to-use guidance, no exclusions, and no mention of when the sibling get_keyword_performance_report would be preferred instead. Usage is only implied by the phrase 'for an ad group', which an agent must interpret on its own.

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