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

Annotations already declare read-only, idempotent, and non-destructive behavior, so the description is not burdened with safety disclosure. It adds valuable context about the data source (Helious live ship tracking) and the segmentation (tanker/cargo) beyond the annotations. This extra detail helps the agent understand what the tool actually returns, though it does not describe pagination or output format.

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 a single sentence that front-loads the core purpose ('ships through the Strait of Hormuz per day') followed by supporting details. Every phrase contributes meaning, with no fluff or repetition. It is highly concise and well-structured.

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 retrieval tool with one optional parameter and no output schema, the description provides sufficient context: daily resolution, segmentation, and data source. It does not describe the exact return format, but given the simplicity and annotations, the agent can infer the likely shape. Slight gap is that it doesn't clarify whether the result is a time series or single aggregate, but this is minor.

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?

The input schema fully documents the single 'days' parameter as 'How many days back,' achieving 100% coverage. The description adds no additional meaning about how the parameter behaves (e.g., defaults, allowed range, or interaction with the daily data). Therefore, the description does not enhance the schema's parameter semantics.

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 identifies the tool as providing daily ship transits through the Strait of Hormuz, segmented by tanker and cargo. This is specific and distinguishes it from sibling tools, which focus on other market data. The mention of 'Helious' and 'live ship tracking' adds provenance without ambiguity.

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 implies usage when Hormuz transit data is needed, but provides no explicit guidance on when to use this tool versus alternatives. It does not mention situations where other tools would be more appropriate, nor does it list alternatives. The 'per day' phrasing hints at temporal resolution but not at selection criteria.

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