ads_campaign_performance

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

With no annotations provided, the description carries the burden, and it does well: 'report' establishes a read-only operation, and the metrics list plus 'sorted by cost descending' and 'restrict to ENABLED campaigns' disclose concrete output and filtering behavior. It could go further on auth or omitted customer_id behavior, but the core behavioral profile is clear.

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 minimal and efficient: the purpose and key metrics are front-loaded, and the Args section is neatly formatted with one line per parameter. Every sentence earns its place with no filler.

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?

An output schema exists, so return value details are not required. The description covers all key metrics, sorting, and parameter semantics. The only gaps are the lack of explicit usage differentiation from sibling tools and the ambiguity around customer_id being nullable in the schema despite being described as the account id.

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%, but the description compensates fully by explaining every parameter: customer_id is a 10-digit account id, date_range is a GAQL date constant with examples, limit caps the number of campaigns, and only_active restricts to ENABLED campaigns. This adds meaning beyond the raw schema defaults and types.

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 (campaign performance) and the specific metrics returned (impressions, clicks, CTR, cost, conversions, CPA, ROAS, conversion value), differentiating it from the sibling ads_keyword_performance tool. The word 'report' plus the metrics list leaves no ambiguity about what the tool does.

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 implies use for campaign-level performance reporting but does not explicitly state when to choose this over alternatives like ads_keyword_performance or ads_search_terms_report. It provides parameter context but no when-to-use or when-not-to-use guidance.

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