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

With no annotations, the description must carry the full behavioral burden. It lists the cost components, but does not disclose the calculation formula, how discount and tax are applied, whether shipping is per-order or per-unit, or how currency is used. The phrase 'explicit discount' hints that discount is a direct input, but the actual behavior remains ambiguous.

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?

One concise sentence, front-loaded with the core operation and followed by the cost components. There is no filler or redundant elaboration beyond the slight rewording of the title.

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 tool with no annotations and no output schema, the description is too thin. It omits the formula, the role of quantity, the currency parameter, and the return value. An agent would have to guess important behavioral details such as whether tax is computed on the discounted subtotal.

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 0%, so the description must compensate. It identifies shipping, tax, and discount as cost components, which adds meaning beyond the bare property names. However, it does not explain the currency parameter, nor whether tax/discount are absolute amounts or rates, so compensation is incomplete.

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 states a specific verb ('calculate') and a specific resource ('delivered cost per unit'), then names the included components (shipping, tax, explicit discount). This makes the operation distinct from siblings like calculate_real_discount or normalize_pack_value, which address different calculations.

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 gives no guidance on when to prefer this tool over alternatives, nor does it state exclusions or prerequisites. While the name implies it is for delivered unit cost, there is no explicit 'use this when...' context, and the sibling tools are not mentioned.

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