Cross-Platform Performance Report

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

Annotations already indicate readOnly, destructiveHint false, and idempotent. The description adds that it returns a comprehensive structure (period, totals, by_platform, campaigns, etc.), which provides behavioral context beyond annotations. However, it does not detail pagination or potential rate limits, but that is minor given annotations cover safety.

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 compact, front-loaded with the core purpose, and each sentence adds value: first sentence defines purpose, second lists inputs, third lists outputs, last gives usage guidance. No wasted words.

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?

Despite no output schema, the description fully describes the return structure with key fields. Given the tool's complexity (5 parameters, nested objects, cross-platform aggregation), the description covers all necessary aspects for an agent to understand and invoke it 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 coverage is 60% but the description enumerates all parameters with value constraints (e.g., sort_by enum values, date_format YYYY-MM-DD, default for date_range). It adds meaning by specifying that date_range defaults to last 7 days and that sort_by includes 'clicks' even though the schema has it, but enriches the context.

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 it aggregates performance metrics across Google Ads and Meta Ads into a unified view. It uses a specific verb ('aggregate') and resource ('Cross-Platform Performance Report'), and it distinctly differs from siblings like 'analytics' tools or single-platform reports.

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 explicitly says this is 'the entry point for most analysis workflows', implying it should be used first before more specific tools. It enumerates optional filters and parameters, providing clear context for when to use it versus other analysis tools like anomaly_detect or audience_insights.

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