google_ads_device_performance

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

No annotations are provided, so the description must fully disclose behavior. It only states a read operation ('Get performance') without detailing pagination, error handling, or data availability. The return type is vaguely described as 'Performance breakdown by device'.

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 brief and to the point, using a standard docstring format with an example. Every sentence adds value, and the structure is clear. Slightly verbose due to the example but acceptable.

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 there is an output schema (not shown), return value details are not required. The description covers the basic purpose and parameters adequately for a tool with 3 parameters and 0% schema coverage. It could be improved with more detail on date_range options.

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 0%, so the description adds meaning beyond the schema. It explains customer_id format, optional campaign_id, and default date_range with an example. However, it does not enumerate valid date_range values or clarify the nature of campaign_id.

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 'Get performance by device type (mobile, desktop, tablet)', which is a specific verb+resource combination. It distinguishes itself from sibling tools like google_ads_campaign_performance or google_ads_account_performance by focusing on device breakdown.

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 an example and indicates optional campaign_id filtering, implying usage when device-level breakdown is needed. However, it does not explicitly state when to use this tool over other performance tools or mention any prerequisites or limitations.

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