google_ads_device_analyze

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

No annotations are provided, so the description carries the full burden. It explicitly states 'Read-only,' describes the exact return shape including edge cases (cpa is None when conversions == 0, empty devices list with a message field when no data), and discloses insight trigger conditions. This is comprehensive behavioral disclosure beyond what a schema could offer.

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 packed with essential information—purpose, return structure, edge cases, sorted order, insight conditions, and alternatives—all in a compact paragraph. Every sentence earns its place; there is no fluff 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?

Given no output schema and only a 3-parameter input schema, the description fully compensates by specifying the return object structure, sorting, and edge-case behavior. It also covers the tool's place among siblings, making it complete for an AI agent to select and invoke correctly.

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 100%, and the schema itself provides detailed parameter semantics (default period, campaign ID format, fallback for customer ID). The tool description adds no parameter-specific guidance, so the baseline score of 3 is appropriate—it neither harms nor adds beyond the schema.

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 opens with a specific verb and resource: 'Compare Google Ads campaign performance across device segments (Desktop / Mobile / Tablet).' It clearly distinguishes from sibling tools by naming alternatives for bid adjustments and schedule targeting, so the purpose is unambiguous.

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?

Explicitly states when to use this tool vs alternatives: 'For applying device bid modifiers use google_ads_bid_adjustments_update or google_ads_device_targeting_set; for the raw ad-schedule criteria ... use google_ads_schedule_targeting_list.' This provides direct exclusions and alternatives, leaving no doubt about use cases.

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