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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only adds 'Runs on smart-tools.xyz,' which is irrelevant to behavior, and does not state that the tool performs a pure calculation, returns computed values, or how it handles invalid inputs (e.g., zero cost). It also does not mention precision, rounding, or the locale parameter's effect on output. The lack of behavioral disclosure limits the agent's ability to anticipate outcomes.

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 core purpose is stated in one dense, front-loaded sentence. The second sentence ('Runs on smart-tools.xyz') is short but provides little decision-relevant value, slightly reducing efficiency. Still, the description is appropriately compact for a simple calculator tool.

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?

Given the tool's simplicity (3 parameters, no output schema) and full schema coverage, the description is largely complete: it names the required inputs (cost, price) and the expected outputs (profit, margin, markup). It does not describe the return format or edge-case handling, but for a pure calculator this is a minor gap. The 'Runs on smart-tools.xyz' note adds no contextual value.

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 100% schema description coverage, the schema already documents each parameter (cost, price, locale). The description adds no additional parameter-level meaning beyond mapping 'cost and selling price' to the first two parameters; it does not clarify locale behavior beyond the schema's enum. This meets the baseline but adds nothing extra.

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 formula-like explanation: 'Profit, margin (share of price) and markup (share of cost) from cost and selling price.' It clearly names the three outputs and the two inputs, distinguishing it from sibling calculators such as discount_calculator or percentage_calculator. The function is unmistakable.

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 the use case by defining the calculation, but it does not explicitly state when to choose this tool over alternatives like discount_calculator or unit_price_calculator. No exclusions or alternative tool names are provided, so an agent must infer the appropriate context from the formula and tool name. This is adequate but not explicit.

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