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

Annotations already declare readOnlyHint=true and openWorldHint=false. The description adds depth by explaining the computational methodology, the update frequency ('Updates: weekly'), and the returned fields, giving the agent a richer behavioral model without contradiction.

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 three sentences, front-loads the core definition, includes usage triggers, and closes with update frequency. Every sentence provides essential information with no 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?

The description covers what the tool returns, when to use it, and update frequency, while the schema fully documents the one parameter. Minor gap: it does not explicitly state the default snapshot behavior, but that is addressed in the schema, making the overall tool well-specified.

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% for the single optional 'days' parameter, with details on history series, time range, and Gold tier requirement. The tool description itself adds no additional parameter information, so the schema carries this dimension adequately.

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 tool returns a 0-100 US marine and port freight cost-pressure score, derived from vessel AIS dwell-time distributions and percentile-ranked since 2008. It also lists the exact output fields, making the purpose specific and distinguishable from sibling indices.

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 says 'Call when the user asks about port congestion, container dwell times, ocean freight costs, or supply-chain bottlenecks, or when timing inventory builds, warehouse commitments, or holding-cost budgets.' This provides clear, actionable usage context.

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