Get shipping options

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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description adds real value by flagging that returned prices are estimates and that accuracy scales with address completeness. It says nothing about how live/volatile the pricing is, whether results can vary between identical calls, or failure behavior for an invalid pod_package_id.

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?

Two sentences, front-loaded with the purpose and followed by the most decision-relevant input constraint. No filler, no restatement of the title, and nothing an agent must skip past to find the useful part.

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?

With no output schema, the description does carry the return-value burden and handles it reasonably (price and delivery estimates). But for a nested, 3-parameter tool with only 33% schema coverage, the unaddressed currency parameter and unelaborated per-book item structure leave gaps an agent would hit in practice.

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 33% schema coverage the description must compensate, and it partially does: "some books" maps to line_items, "destination" maps to shipping_address, and the note that only country is required clarifies the nested required field. But the currency parameter is never mentioned, and the required per-book fields (pod_package_id, page_count, quantity) are not explained beyond the schema's own text.

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?

"List the shipping levels available for some books to a destination, with price and delivery estimates" gives a concrete verb (list) and resource (shipping levels) plus the two things returned. It is clear on its own, but it never distinguishes itself from the nearest sibling (calculate_print_job_cost), leaving the agent to infer which one to call for a cost estimate.

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 second sentence gives genuinely useful input guidance ("Only the country is required; a fuller address gives more accurate results"), which is a precision/cost tradeoff the agent can act on. However, there is no statement of when this tool applies versus calculate_print_job_cost or get_print_job_costs, so usage context is only implied.

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