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

Beyond the readOnlyHint and openWorldHint annotations, it discloses the billing model ($0.002 in USDC per successful call via x402 on Base, Solana or Arc) and critically that failed calls are not charged, plus the data-source limitation. These are exactly the behavioral traits an agent needs before invoking a paid external call.

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?

Purpose, return fields, and source are front-loaded, followed by coverage restriction and pricing. It is a single dense paragraph with little waste, though the payment-rail enumeration makes the closing sentence long.

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?

An output schema exists, so return values need no explanation, and the description covers source, coverage limits, slug format, and cost/billing behavior. An agent has everything needed to decide and call 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 description coverage is 100% and the single 'port' parameter is already documented as a lowercase hyphenated slug with an example. The description's extra examples (ako, long-beach) add only marginal value over the schema, so baseline 3 applies.

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 resource (weekly port congestion figures) with the exact metrics returned (median waiting time, average vessels waiting per day, congestion category, week-on-week change), and names the source (Portcast's public port page). This clearly separates it from siblings like logistics_port_call_schedule or logistics_seaport_unlocode, which cover different port-adjacent data.

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 sets concrete usage boundaries: only free public page data, not the paid API, and only for ports Portcast publishes, with the slug convention spelled out. What's missing is an explicit pointer to an alternative sibling when the port isn't covered, but the context an agent needs to decide applicability is present.

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