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

Annotations already establish read-only, idempotent, non-destructive behavior, and the description adds no further side-effect or operational context such as costs, errors, or special cases. The mention of tiers and the free-shipping threshold describes output content rather than a behavioral trait, so no significant extra value beyond the safety annotations is added.

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?

A single, front-loaded sentence starts with the action ('Return the exact shipping cost') and packs the required parameters and outputs into one efficient clause. There is no filler, repetition, or tangential information.

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 three-parameter read-only tool with a full input schema, complete annotations, and an output schema available, the description supplies all context an agent needs to decide and invoke correctly. It explains the key derived output, the free-shipping threshold gap, that a caller would otherwise not anticipate.

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 coverage is 100% with detailed descriptions for all three parameters, so the schema carries the meaning. The description restates the parameter concepts but adds no new format, unit, or edge-case information beyond the schema.

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 names a precise action (return exact shipping cost), a clear resource (a specific shop, country, and cart value), and the distinct outputs (all shipping tiers and the gap to free-shipping). This differentiates it from sibling tools such as get_best_price, which concern product pricing rather than shipping cost.

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?

It clearly implies when to use the tool: whenever the agent needs the shipping cost for a known shop, country, and cart value. It doesn't explicitly list alternatives or exclusion conditions, but the strong context makes the intended use obvious.

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