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

Annotations already indicate read-only, idempotent, open-world, and non-destructive behavior. The description adds value by disclosing determinism, the paid-resource cost ('$0.002 USD per call'), and the nature of outputs ('break-even price and sensitivity outputs').

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 front-loaded with the core function, followed by usage guidance, exclusions, and pricing. It is compact, though there is slight redundancy between the first sentence and the 'Use this tool when...' clause, and the phrase 'when check whether' is a minor grammar issue.

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 6-parameter calculation tool with no output schema, the description supplies the essential context: purpose, inputs, outputs, exclusions, and cost. It does not fully specify input formatting or return value details, but the combination of rich annotations and the description is sufficient for correct selection and basic invocation.

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?

With 0% schema description coverage, the description must carry the parameter semantics. It enumerates all six input categories (price, variable costs, payment fees, retry probability, expected retry cost), but it does not explain the structure of the variable_costs array, units, or optionality, so it only partially compensates for the schema gap.

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 opens with a specific verb and resource: 'Computes deterministic per-call contribution economics'. It also distinguishes itself from siblings by stating 'this is product-level economics, not supplier routing', which is critical among many similarly named preflight/routing tools.

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?

It gives an explicit invocation condition: 'Use this tool when check whether a candidate paid agent product has positive contribution economics before publication.' It also provides explicit exclusions: 'Do not use it for unrelated general knowledge or unsupported legal, identity, sanctions, fraud, contractual, or regulatory adjudication.'

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