Look up a vessel by registration number

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

With no annotations, the description carries the full burden. It discloses key behaviors: normalization of registration numbers and that the response includes a web_url. It does not cover error cases or authentication requirements, which would enrich transparency, but the provided information is useful and non-obvious.

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 well-structured, with the primary purpose stated up front followed by normalization details and return value. Two sentences deliver all necessary information without redundancy.

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 simple single-parameter lookup tool, the description covers normalization and return contents. It does not explicitly address not-found behavior or response format beyond mentioning web_url, but these are minor gaps given the tool's simplicity and lack of output schema.

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% (the parameter has a description and example), giving a baseline of 3. The description adds value beyond the schema by explaining normalization (e.g., handling dashes, spaces, Latin/Cyrillic forms), which informs the agent how to format or interpret the registration_number parameter.

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 verb ('lookup') and resource ('vessel') and clarifies the exact-match behavior with normalization. It distinguishes from siblings like search_vessel_registries by emphasizing 'exact' lookup, making the tool's role clear.

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 implies when to use this tool (when you have an exact registration number, given normalization) but does not explicitly mention when not to use it or direct the agent to alternatives like search_vessel_registries for partial matches. The usage context is inferable but not stated.

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