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

With annotations only indicating read-only, idempotent, and non-destructive behaviors, the description significantly adds transparency: it discloses partial results, explains when missing components count as zero, details the mandatory vs. additional charge breakdown, and even mentions the payment requirement and 402 error. This goes far beyond the annotation hints and provides critical behavioral context.

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?

Although lengthy, every sentence earns its place: it front-loads the core action, then covers critical caveats, return structure, and an important accounting rule. The structure is logical, with the 'IMPORTANT' note appropriately highlighted. No redundancy is present.

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?

Given the tool's complexity, the description is remarkably complete: it details the return object components, explains the meaning of 'verified', 'coverage', and 'data_gaps', quantifies payment, and clarifies mandatory vs. additional cost calculations. Without an output schema, the description fully compensates by specifying the return structure and semantics.

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 baseline is 3. The description adds context by linking 'detention_days' to 'requested demurrage/detention exposure' and clarifying that the total includes 'requested D&D', which is not explicit in the parameter schema. While the schema already documents each parameter, this semantic linkage provides extra meaning, justifying a 4.

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 tool 'Calculate a published multi-component shipping-cost estimate' from certified dependencies, which is a specific verb+resource. It further distinguishes itself from siblings by explicitly listing component-specific tools, leaving no ambiguity about its overall function.

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 provides explicit when-to-use guidance by stating 'For individual components, use shippingrates_rates, shippingrates_surcharges, shippingrates_local_charges, and shippingrates_dd_calculate.' It also clarifies the interpretation context ('A market index is not a carrier quote') and instructs users to inspect fields before quoting, effectively covering both usage and exclusions.

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