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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is largely covered; the description still adds the non-obvious fact that this read is a POST to /v3/list_shipping_options_multiple and that no order or billing occurs. Returned content ('shipping_code values') is disclosed, though error behavior for invalid addresses and any rate limits are not.

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?

Four compact clauses, each doing distinct work: purpose, inputs, return value, side-effect disclaimer, followed by the endpoint. Purpose and safety constraints are front-loaded with zero filler.

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 steps up by naming what comes back (shipping_code values), and it clarifies the non-mutating nature of a POST endpoint. It stops short of noting behavior on an invalid/unserviceable address, which is the main remaining gap for a nested-payload quoting tool.

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 100%, so the schema already documents recipient fields, state_code vs province, country_code format and the 1-999 quantity range. The description only restates the two top-level groups at a high level, adding no syntax or validation nuance beyond the schema — baseline 3.

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?

States a specific verb+resource ('Shipping options and rates'), scopes it precisely ('for one prospective order'), and enumerates the inputs (recipient address plus SKUs and quantities). The phrase 'prospective order' plus 'Nothing is ordered or billed' makes it unmistakable versus list_orders/get_order/pending_orders siblings.

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 implies the pre-purchase quoting scenario ('an order would need', 'Nothing is ordered or billed') but never names an alternative such as validate_address for address checking or get_prices for product pricing, nor states prerequisites. Usage is inferable but not spelled out.

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