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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false. The description adds no behavioral context beyond that—no rate limits, auth needs, output format, or constraints. It does not contradict the annotations.

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 first sentence is front-loaded and efficient. The second sentence is a promotional link to an external website that does not help an agent invoke the tool and does not earn its place in the definition.

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?

For a simple three-required-parameter calculator with strong annotations and full schema coverage, the description sufficiently explains the purpose and names the outputs (over-reporting and true blended ROAS). It lacks output format details, but no output schema exists and the tool is straightforward.

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% and all three parameters have descriptive schema text. The description loosely maps to platformRevenue and actualRevenue by naming platform-claimed and backend revenue, but adds no syntax, units, or meaning 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 names a specific verb (Compare) and specific resources (summed platform-claimed revenue vs actual backend revenue) and states the outcome (over-reporting and true blended ROAS). It is clearly distinct from generic ROAS calculators, though it does not explicitly name any sibling tool as an alternative.

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 implies usage by stating what it compares, but gives no explicit when-to-use guidance, no prerequisites, and no alternatives. An agent can infer the context, but would have to decide on its own when this modeler is preferable to siblings like roas_calculator.

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