Product margin calculator
| Name | Required | Description | Default |
|---|---|---|---|
| cost | Yes | What one unit costs you. | |
| price | Yes | What you sell one unit for. | |
| quantity | No | Units, for totals. | |
| fixedCosts | No | One-off costs (tooling, setup, launch) for the break-even quantity. | |
| targetMarginPct | No | A margin you want; its price is added to the price ladder. |
Changes observed during successful MCP inspections.
Input schema / properties / cost / descriptionAdded value: +"What one unit costs you."Input schema / properties / fixedCostsAdded value: +{
+ "description": "One-off costs (tooling, setup, launch) for the break-even quantity.",
+ "minimum": 0,
+ "type": "number"
+}Input schema / properties / price / descriptionAdded value: +"What you sell one unit for."Input schema / properties / quantityAdded value: +{
+ "description": "Units, for totals.",
+ "minimum": 0,
+ "type": "number"
+}Input schema / properties / targetMarginPctAdded value: +{
+ "description": "A margin you want; its price is added to the price ladder.",
+ "maximum": 99.9,
+ "minimum": 0,
+ "type": "number"
+}Input schema / properties / cost / minimumAdded value: +0Input schema / properties / price / minimumAdded value: +0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The annotations already declare this to be a read-only, idempotent, non-destructive, closed-world calculation, so safety behavior is covered. The description adds no further behavioral context, such as what computed values are returned or how fixed costs and target margin affect results.
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 phrase is concise and has no wasted wording, but it is under-specified for a five-parameter calculation tool. It lacks front-loaded detail about what is calculated or what output to expect.
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?
There is no output schema, and the description does not explain the calculation outputs or how optional parameters like quantity, fixedCosts, and targetMarginPct are used. For a calculator with multiple optional inputs, the definition is too sparse to be complete.
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 100%, so the parameter meanings are already well documented in the input schema. The description adds no additional semantics beyond the schema, which is acceptable at baseline when the schema does the heavy lifting.
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 'Product margin calculator' largely restates the tool name and annotation title rather than specifying a distinct operation or resource. It does not differentiate this tool from close siblings such as business_profit_margin or business_break_even.
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?
No when-to-use guidance is provided, and there are no exclusions or alternatives named. An agent is left to infer whether this is for gross margin, markup, break-even, or price-ladder calculations, especially given the nearby business_profit_margin and business_break_even tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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