get_package_dimensions

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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false. The description adds valuable context beyond that: it costs 1 credit, it returns structured fee-category data, and it is the fee-calculation source rather than a human-readable description. No contradiction with annotations.

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?

Every sentence earns its place: the first defines the resource, the second provides the routing decision with an explicit alternative, and the third states cost. It is front-loaded and free of 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?

The description covers what the tool returns, when to use it, what to avoid, the key alternative, and the cost. With no output schema, it lists the return attributes but omits units of measurement and error behavior; however, these are minor gaps given the tool's simple read-only nature.

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 already provides 100% coverage for both parameters, including ASIN format and domain enum/default. The description adds no parameter-specific semantics beyond reiterating the tool's purpose. Per the baseline rule for high schema coverage, a 3 is appropriate.

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 ('Get'), a precise resource ('a product's precise physical and logistical attributes'), and names the exact attributes: package height, width, length, weight, and Amazon fee category. It also positions the tool as the FBA fee-estimation and shipping-cost tool, clearly distinguishing it from get_product_detail, which returns a human-readable dimensions string.

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 explicitly says when to use the tool ('when the question is about shipping, storage, FBA fees, or warehouse planning') and when not to ('Do NOT use it for general product info'). It names the alternative tool (get_product_detail) and explains the differentiator, giving an agent a concrete decision rule.

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