Get Campaign Performance

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

Annotations already declare readOnlyHint=true, and the description adds genuinely useful behavior beyond that: results are ordered by cost descending, and cost/budget fields are in micros requiring division by 1,000,000. This is real operational context, not a restatement of the safety hint.

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 tight paragraphs, both front-loaded: the metric list first, then the ordering and unit convention. No filler sentences and nothing repeated from the schema.

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 structure needn't be explained, and the description still covers ordering and unit interpretation. Given the low-complexity read-only nature of the tool, this is close to complete; only the sibling routing to finer-grained reports is missing.

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 coverage is 100%, so the baseline is 3, but the description goes further by documenting the micros unit convention for cost and budget fields, which is a non-obvious domain quirk not present in the schema property descriptions.

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?

States a specific verb+resource ('Campaign-level performance report') and enumerates the metrics returned (impressions, clicks, CTR, cost, conversions, conversion value, status, bidding strategy, daily budget). The 'campaign-level' scoping implicitly separates it from sibling reports like get_ad_group_performance and get_keyword_performance, though those siblings are never named.

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?

Usage is implied by the report name and by the mention of date granularity, but there is no explicit 'use this when...' statement, no exclusions, and no pointer to the ad-group or keyword-level reports that cover the same ground at finer granularity.

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