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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the description does not need to restate safety. It adds value by describing the specific data returned (terminal list with name, company, coordinates, etc.) and the constraint of providing exactly one identifier. It does not contradict annotations and provides meaningful behavioral context beyond the structured 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 two sentences, with the primary action and return fields front-loaded, followed by usage guidance. Every sentence earns its place with no redundancy or filler. The structure is clean and immediately scannable.

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?

The tool has an output schema, so return value details are already defined. The description covers purpose, return fields, lookup methods, and the alternative tool. It leaves nothing essential unexplained for an agent to correctly invoke it. The 'exactly one' constraint is explicitly stated, and the read-only nature is covered by annotations.

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% — both parameters (uuid and unlocode) have detailed descriptions including the 'exactly one' rule and format examples. The description reiterates this but does not add new information beyond what the schema already provides. The baseline of 3 is appropriate because the schema carries the full semantic load.

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 explicitly states the tool returns detailed information for a single port, enumerates the exact fields (identity, country, UN/LOCODE, classification, coordinates, maritime area, terminals), and differentiates it from sibling find_ports by specifying the lookup key (uuid or UN/LOCODE). This is a clear, specific verb+resource description that leaves no ambiguity about what the tool does.

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 explicitly states when to use this tool versus find_ports: 'To search for a port by name or location, or when you don't have an exact identifier, use find_ports first.' It also clarifies that this tool requires an exact identifier (uuid or unlocode) and that exactly one must be provided. This is strong guidance with a clear exclusion and alternative.

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