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

Beyond the read-only annotations, it discloses that no account is needed, prices are public rates at quote time, and the response includes up to six cheapest services with price, transit time, and a website link for buying the label. This gives the agent useful behavioral context for interpreting and presenting results.

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?

The description is front-loaded with the core purpose, then adds only relevant usage and return details. Despite being several sentences, each part contributes useful information for invoking or interpreting the tool.

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 adequately explains what is returned: up to six cheapest services, price, estimated transit time, and a quote link. Together with the annotations and fully documented schema, an agent has enough context to call and present this tool correctly.

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%, so the schema already documents each parameter. The description still adds meaningful guidance beyond the schema, especially unit conversion for weight and dimensions and the default 30 x 20 x 10 cm box assumption when dimensions are omitted.

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 states a specific verb and resource: get live shipping prices for one parcel from several named carriers. It clearly distinguishes this from compare_shipping_rates by positioning that sibling as the account-price alternative.

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 explicitly says when to use this tool: public rates, no account needed, origin/destination postal codes and weight required. It also names the alternative when the user is signed in: compare_shipping_rates returns their own account prices instead.

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