vessel_details

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

With no annotations, the description carries the full behavioral burden. It discloses the response shape, the error behavior when no unique match is found, that snapshot data may be stale, and the meaning of null fields. This is strong behavioral context, though it does not mention authentication, rate limits, or explicit read-only guarantees.

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?

Every sentence earns its place: the first states the operation and accepted inputs, the second explains the return and error shape, and the third clarifies two important data semantics. It is compact, well-organized, and free of filler.

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 one-parameter lookup tool with an output schema and no annotations, this description covers all the essentials: how to query, what the response contains, what errors mean, when data may be stale, and how to interpret null fields. An agent has enough guidance to invoke it 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 schema already fully describes the query parameter and its non-blank requirement. The description largely restates this instead of adding new semantic details like case sensitivity or minimum partial-name length, so it meets the baseline but does not exceed it.

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 ('Look up'), a single resource ('a single vessel'), and the two query modes (exact MMSI or partial name). This makes it immediately distinguishable from sibling tools like search_vessels, which imply broader or multi-result behavior.

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 clearly states when to use the tool: to look up one vessel by MMSI or name. It does not explicitly name alternatives or exclusions, but the single-vessel scope plus the sibling list provides enough context. It lacks an explicit 'use search_vessels when you need multiple results' statement.

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