get_device_performance

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

With no annotations, the description carries the full burden of behavioral disclosure. It implies a read-only operation via 'Return' but does not mention permissions, data freshness, or any side effects. This is adequate but lacks depth.

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 two concise sentences that front-load the purpose and immediately provide a practical use case. Every word is useful, with no redundancy or filler.

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?

The tool has a fully documented input schema (100% coverage) and an output schema, so the description does not need to explain return values. It adds context through the use-case statement, which helps the agent place the tool in a workflow. It is complete for this tool's complexity, though it could briefly mention any prerequisites or limitations.

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?

The input schema already provides complete descriptions for all three parameters (customer_id, days, login_customer_id), so the description adds no additional parameter semantics. The description's focus on device segmentation is unrelated to parameter-level details, so it does not go 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 'Return campaign performance segmented by device' and explicitly names the device types (MOBILE, DESKTOP, TABLET). This distinguishes it from sibling tools like get_geo_performance and get_campaign_performance, which focus on different breakdowns.

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 explicit use case: 'identify bid adjustment opportunities and diagnose mobile vs. desktop conversion rate gaps.' This gives clear context for when to use the tool, though it does not explicitly mention alternatives or when not to use it.

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