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

With no annotations, the description carries the behavioral burden and does a solid job: it discloses the paywall behavior (HTTP 402 when unpaid), the payment requirement ($0.05 USDC on Base), and that the same URL returns JSON after a valid X-PAYMENT. It does not describe response contents or failure modes beyond 402, but the core payment-gated behavior is clear.

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 endpoint and payment requirement. Every sentence conveys operational information, though 'Not a new SKU' is somewhat cryptic and could be clarified or removed.

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?

This is a simple one-parameter, no-output-schema tool, and the description provides the essential context: payment amount, recipient, HTTP behavior, and response type. It lacks detail on the JSON structure, but for a low-complexity paid endpoint this is a reasonably complete picture.

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% and the single x_payment parameter is already well documented as an optional X-PAYMENT header value. The description reinforces that a valid X-PAYMENT unlocks JSON but adds little meaning beyond the schema.

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 identifies a specific HTTP GET endpoint and resource ('USCG D7 / Southeast LNM') and indicates it returns JSON after payment. The 'mariners-d7' naming plus 'USCG D7' distinguishes it from sibling tools like mariners-d8 and mariners-d11, though the description does not explicitly name those alternatives.

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?

No guidance is given for when to use this tool versus the many sibling tools. The phrase 'Not a new SKU' hints at product positioning but does not help an agent decide between mariners-d7 and related mariners tools.

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