google_ads_monitoring_cpa_goal

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

With no annotations, the description fully discloses behavioral traits: read-only, hardcoded to last 7 days, current_cpa is None when conversions==0, threshold logic for status (target_cpa * 1.2), and that the return includes wasteful terms from cost_analysis. It also notes customer_id falls back to configured credentials.

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 a single paragraph that front-loads the purpose and then details return structure and key behaviors. It is informative but could be more structured with bullet points or clearer separation of sections. Still, every sentence adds value.

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 the tool has 3 parameters, no output schema, and moderate complexity, the description is highly complete. It explains the return object structure, status thresholds, edge cases (conversions==0), and sources for inputs. It also references sibling tools for required pre-steps (e.g., campaign_id retrieval).

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% for all 3 parameters. The description adds value by explaining the customer_id fallback, source for campaign_id (via google_ads_campaigns_list), and threshold semantics for target_cpa (1.2 multiplier for warning/critical). This goes beyond the schema's basic 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?

The description clearly states the tool evaluates a campaign's CPA against a target, integrates cost increase analysis, and returns a structured result. It explicitly distinguishes itself from siblings like google_ads_health_check_all and google_ads_monitoring_cv_goal, which have different scopes (account-wide vs daily CV count).

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 provides explicit guidance on when to use this tool (campaign-level CPA monitoring) and when to use alternatives: for account-wide rollup, use google_ads_health_check_all; for daily CV count, use google_ads_monitoring_cv_goal. It also clarifies that target_cpa is required and does not fall back to bid strategy or actual CPA.

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