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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds useful context beyond that: the OFAC SDN source, the 1,524-ship dataset, list mode, and cost/auth details ('free, no key', '$0'). It remains fully consistent with the read-only hints.

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 screening action and primary use case. The list mode, source, and cost details all earn their place, though the final '$0' slightly redundantly repeats 'free, no key'.

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 read-only screening tool with one generic optional parameter and an output schema, the description covers purpose, usage context, data source, scale, and modes. It does not define the input payload structure explicitly, but the schema plus the output schema fill most of that gap.

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?

The input schema only says 'parametros del producto (JSON o texto)', which is generic. The description compensates by explaining that the input is a vessel IMO or name and that a list mode exists, giving the parameter real meaning. It stops short of specifying the exact JSON format, but the optional single parameter keeps this reasonable.

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 names a specific verb ('screen') and a precise resource ('any vessel (IMO or name) against the OFAC SDN sanctioned-vessels list'), and it adds the list-mode snapshot variant. This clearly distinguishes it from the generic-sounding sibling sanctions_screen.

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 gives concrete when-to-use context: 'the compliance check before touching tanker/shipping trades or chokepoint bets.' However, it does not mention alternatives or when not to use this tool, even though sanctions_screen exists as a closely related sibling.

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