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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered structurally. The description adds nothing beyond that: no statement that the result is a pure arithmetic estimate, no mention of currency or units, and no indication of what the returned value looks like or whether rounding applies.

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?

Three words is concise in the trivial sense, but the rubric penalizes under-specification. There is no front-loaded scope, units, or formula, so brevity here is a deficit rather than an efficiency.

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 3-parameter calculation tool with no parameter descriptions, no output schema, and a required-parameter structure that hides the formula, the description is wholly inadequate. An agent could call it with the right types but cannot know what the numbers mean or how to interpret the result.

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% across three parameters, and the description supplies no compensating meaning. Critically, it never explains how base, weightKg and ratePerKg combine into the estimate (e.g. base + weightKg * ratePerKg), which is precisely the information an agent cannot infer from names and types alone.

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?

"Shipping cost estimator" just rephrases the tool name (business_shipping_estimate) without adding detail. It tells the agent nothing about what kind of shipment, carrier, region, or cost model is involved, and nothing distinguishes it from the many other numeric business calculators in the sibling list.

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?

There is no statement of when to use this instead of alternatives. The sibling set contains overlapping calculators (business_break_even, business_marketplace_fee, business_profit_margin), and the description offers zero routing guidance between them.

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