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

Annotations already declare the operation read-only, idempotent, and non-destructive, so the safety profile is covered. The description adds useful behavioral context—carrier coverage and cheapest-first ordering—but does not discuss rate validity, account requirements, or origin assumptions.

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?

One tightly written sentence with no filler, front-loading the carrier scope and output ordering.

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 rate-quoting tool with no output schema, the description gives only a minimal output summary (services, price, cheapest first). It omits whether returned rates include IDs needed by buy_label, currency, or delivery estimates, and says nothing about the missing origin/origin-default context.

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 only 50%, and the description adds no parameter meaning at all. Required fields like to_zip and weight_oz are documented in the schema, but dimensions and packaging have no descriptions anywhere, and the description does not compensate.

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 clearly states the resource (USPS and UPS services with prices) and the scope (one package), which distinguishes it from quote and label-purchase siblings. It does not explicitly name alternatives, keeping it below a 5.

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—an agent can infer this is for comparing shipping rates before buying a label—but there is no explicit when-to-use versus siblings like get_pickup_quote or buy_label. No exclusions or prerequisites are stated.

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