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

Beyond the annotations (readOnly, idempotent, non-destructive), the description discloses deterministic scoring, zero contribution for unknown inputs, conditional scoring only when at least one signal applies, immutable UN/LOCODE mapping, payment requirement (returns 402 without payment), and the unchanged API result shape. No contradictions with annotations.

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 well-structured into three concise paragraphs: purpose and data sources, input behavior and alternatives, and payment/return shape. Every sentence carries essential information and avoids redundancy, making it easy to scan.

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 tool with no output schema, the description fully specifies the return object shape, payment terms, error behavior (402 + instructions), and edge cases (unsupported routes return no result). Combined with rich annotations, the description covers all necessary context for an agent to invoke the 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 defines parameters with examples. The description adds behavioral semantics for inputs: 'Unknown inputs contribute zero points' and the chokepoint mapping for specific UN/LOCODE locations, which goes beyond the schema's basic type/length constraints.

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 opens with a specific verb and resource: 'Get a deterministic route-risk score (0-100) from current certified port-congestion measurements and explicit official disruption advisories.' It clearly distinguishes the tool from siblings by mentioning exact measurements and advisory detail tools, and states the exact output fields.

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 explicitly provides alternatives: 'For exact measurements, use shippingrates_congestion. For advisory detail, use shippingrates_congestion_news.' It also states when no result is returned (unsupported routes) and the payment prerequisite, giving clear when-to-use versus when-not-to-use guidance.

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