google_ads_device_analyze

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

Without annotations, the description fully discloses behavioral traits: it is read-only, describes edge cases (cpa is None when conversions==0, insights conditions), return structure (sorted by cost, empty devices list with message), and sorting behavior. No contradictions.

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 concise (5 sentences) and front-loaded with the main purpose. It covers all necessary details without fluff. Minor room for structuring (e.g., bullet points) but very efficient.

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 no annotations, the description is complete: it explains purpose, return format, parameter usage, edge cases, and distinguishes from related tools. An agent can confidently select and invoke this tool.

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?

All three parameters have schema descriptions (100% coverage). The description adds significant value: for period, it suggests shorter windows for recent changes and longer for trends; for customer_id, it explains credential fallback; for campaign_id, it tells how to obtain it ('via google_ads_campaigns_list'). This goes 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 clearly states the tool's function: 'Compare Google Ads campaign performance across device segments (Desktop / Mobile / Tablet).' It uses a specific verb ('compare') and resource ('campaign performance'), and differentiates from siblings by explicitly naming alternative tools for bid adjustments and schedule targeting.

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?

Provides explicit guidance on when to use this tool (performance analysis) and when not to: '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 is a model example of usage guidelines.

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