Get rates

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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so the safety profile is covered. The description adds real behavioral context beyond that: which fields come back (your price, retail price, zone, estimated delivery), the cheapest-first ordering, that services unable to carry the package are excluded, and that no purchase occurs. It doesn't mention rate staleness, caching, or error conditions when no ship-from exists.

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?

Front-loaded with the one-line essence before the detail paragraph, and every sentence conveys a distinct fact (units, dimension rules, filtering, no purchase). A few clauses are packed together densely, but there is no 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 in to describe the returned fields and their ordering, and it covers the conditional parameter requirements and unit conventions for an 8-parameter tool. An agent has enough to call it correctly and interpret the results without further documentation.

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 only 50%, so the description carries useful weight: it ties packaging values to their required dimensions ('Parcel, SoftEnvelope and Irregular need length_in and width_in, a box also height_in'), notes flat-rate packaging needs only weight, and clarifies the ounce unit with a conversion example. It doesn't explain residential or to_country behavior, so it stops short of full compensation.

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?

Names a specific action and resource: a rate quote ('Pirate Ship's Quick Rate Quote') for USPS and UPS services for one package, sorted cheapest first, and closes with 'Nothing is bought' to separate it from the shipment-creation siblings. It's clearly distinguishable from create_shipment and get_pickup_quote without opening the schema, though it never names an alternative tool.

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?

Usage is implied: rate quoting is the pre-purchase step, and 'Nothing is bought' signals it's safe to call repeatedly. But there is no explicit when-to-use or when-not, no mention of prerequisites like a configured default ship-from address, and no pointer to a sibling such as get_pickup_quote or create_shipment.

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