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

Beyond the annotations (readOnlyHint, idempotentHint), the description discloses important behaviors: it uses only explicit operational-disruption terms, returns an empty array instead of inventing alerts, and requires payment via x402 with a 402 response if unpaid. It also specifies the source limitation to Port of Rotterdam and Port of Los Angeles, which is not in the 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 structured in four short paragraphs, front-loading the core purpose and then adding alternatives, payment, and output details. It contains no filler, though it is somewhat dense. Each sentence earns its place, but it could be slightly more compact for a read-only fetch 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?

Given there is no output schema, the description compensates by listing the exact returned fields: { headline, summary, source, port_code, severity, published_at }. It also covers payment behavior, source restrictions, empty-result semantics, and sibling tool distinctions, making the tool's behavior well-specified for an agent.

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 description coverage is 100% with all five parameters documented, so the baseline is 3. The description does not add additional parameter semantics; it only references the output fields (headline, summary, etc.) which include some of the parameter names in context. No further elaboration on parameter usage or syntax is provided.

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 clear verb+resource: 'Get certified shipping-disruption publications from reviewed official port-authority sources.' It explicitly distinguishes from siblings by directing users to shippingrates_congestion for quantitative measurements and shippingrates_risk_score for risk scoring, which clarifies what this tool uniquely provides.

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 states when to use alternatives: 'For quantitative measurements, use shippingrates_congestion. For route-level risk scoring, use shippingrates_risk_score.' It also provides usage context such as the payment requirement and the tool's behavior on empty results, giving clear guidance on when and how to invoke it.

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