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

With no annotations, the description carries the full burden. It does disclose that the tool outputs both contribution margin and fully-loaded margin, which is useful behavioral context. However, it does not explain calculation assumptions, edge cases, input validation, or the structure of the result, which is a notable gap for a complex calculator.

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 concise at two sentences, front-loading the primary verb and object. The first sentence defines the calculation and inputs, the second clarifies the output types. Every word earns its place with no redundancy.

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 tool with 8 required parameters and no output schema, the description gives insufficient context for confident invocation. It does not explain how inputs map to the two margin outputs, what the return structure looks like, or how percentages are interpreted. The agent would likely need to infer important details, making it incomplete for a tool of this complexity.

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 schema has no property descriptions, so the description must compensate. It explicitly names most cost inputs (COGS, shipping, packaging, payment fees, ad spend) and states they are per-unit, which adds meaning. However, it omits platformFeePct, returnsAllowancePct, and price (though price is implicit), providing only partial coverage of the 8 parameters.

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 uses a specific verb ('calculate') and identifies the resource as 'true ecommerce profit margin', listing key cost components (COGS, shipping, packaging, payment fees, ad spend) and clarifying the two output types (contribution vs fully-loaded margin). This clearly distinguishes it from sibling calculators like margin_markup_calculator or break_even_calculator.

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 for ecommerce profit margin calculation with per-unit costs, but does not explicitly state when to use this tool over related alternatives (e.g., product_pricing_calculator, etsy_fee_calculator). No exclusionary statements or alternative tool mentions are provided, leaving the context implicit rather than explicit.

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