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

The description goes well beyond the readOnly/idempotent/non-destructive annotations by disclosing determinism, zero-scoring for unknown inputs, no-result behavior for unsupported routes, immutable UN/LOCODE mapping, payment requirement and 402 response, 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 compact and front-loaded with the core purpose, followed by essential behavioral details, payment info, and return shape. Every sentence adds value without redundancy, making it easy to scan and apply.

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 (paid, deterministic scoring, multiple data sources, specific behavior for unsupported routes), the description covers all necessary aspects: scoring logic, source inputs, mapping, alternatives, payment, and the response shape. Without an output schema, the explicit return shape is essential and provided.

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% with clear descriptions and examples for each parameter, so the baseline is 3. The description adds meaningful context: origin/destination define the route, unknown inputs contribute zero points, and x_payment is the x402 payment proof header, which enriches understanding beyond the schema alone.

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 uses a specific verb ('Get') and resource ('deterministic route-risk score'), clearly scoped to port congestion and official advisories. It explicitly distinguishes itself from siblings by directing users to shippingrates_congestion for exact measurements and shippingrates_congestion_news for advisory detail.

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 provides explicit when-to-use guidance by contrasting with related tools: 'For exact measurements, use shippingrates_congestion. For advisory detail, use shippingrates_congestion_news.' It also explains the behavior for unsupported routes, making selection criteria unambiguous.

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