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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds content context (wait hours, vessels at anchor, low/moderate/high/severe scale) but no additional behavioral detail such as pagination, latency, or failure modes for unknown codes.

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?

Two tightly written sentences, front-loaded with what the tool returns and followed by the one input-format instruction. Every clause carries information; nothing is padding.

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 read-only lookup with a full schema description, safety annotations, and an output schema, the definition covers what an agent needs to call it correctly. Only the lack of selection guidance against sibling tools leaves a small 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?

Schema description coverage is 100% and there is a single required parameter, so the schema already documents the UN/LOCODE format. The description reinforces this with concrete examples (NLRTM, GBFXT, DEHAM, CNSHA), but that is largely a restatement of the schema baseline.

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?

States a specific resource and verb (get current congestion level) and enumerates the returned metrics and congestion scale, so the tool is clearly distinguishable in intent from data-retrieval siblings like get_vessel_position. It never explicitly contrasts itself with those siblings, which keeps it at 4 rather than 5.

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?

Usage is only implied: the description tells the caller to supply UN/LOCODE codes but gives no when-to-use/when-not guidance, no prerequisites, and no routing to or away from alternative tools. Adequate but with a clear gap.

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