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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context: data availability starts 2021-08-10 and only position changes are stored, explaining why stationary periods may have gaps. This goes well beyond what annotations or schema convey.

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 two sentences, front-loads the core purpose, and packs the critical constraints (identifier selection, time range options, data availability, and data gap caveat) with no fluff. Every sentence earns its place.

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?

Given that an output schema exists, return values do not need to be described. The description covers all necessary call semantics: identifier exclusivity, time range selection, date bounds, data availability, and the position-change storage behavior. An agent has enough context to invoke the tool 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%, so the schema already documents each parameter, including formats and the 'exactly one of' and 'days OR from/to' rules. The description reinforces these constraints but does not add meaning beyond the schema, so the baseline score of 3 is appropriate.

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 clearly states the action ('Return the historical track') and the resource ('ordered position records for a single vessel'). It further specifies the identification options (MMSI, IMO, UUID), making it easy to distinguish from sibling tools like get_vessel or estimated_vessel_position.

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 gives clear usage constraints: exactly one identifier must be provided, and the time range must be specified either via 'days' or 'from'/'to', not both. It does not explicitly name sibling alternatives or say when not to use this tool, but the context strongly implies this is for historical tracking versus current vessel data.

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