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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds valuable behavioral context: it clarifies that results are static reference data (not live), explains pagination via next token, and mentions the credit cost. These are beyond what annotations provide, though it does not detail every edge case (e.g., idempotency), which is acceptable given the openWorldHint.

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 dense but well-organized. It front-loads the core search capability, then covers return data, pagination, credits, and alternatives. Every sentence contributes to the agent's decision-making, though it could be slightly condensed without losing information. No fluff is present.

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 the tool's complexity (17 parameters) and the presence of an output schema, the description is complete for an agent to call it correctly. It covers what is searched, the nature of the results, pagination, cost, and when to use alternative tools. The schema handles parameter details, so nothing critical is missing.

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 covers 100% of parameters with descriptions, so the baseline is 3. The description adds meaning beyond the schema by imposing a logical constraint ('Provide at least one search criterion') and clarifying pagination usage (the 'next' parameter). It also summarizes the main filter categories, reinforcing the schema without redundancy.

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's purpose: searching the vessel registry by multiple criteria, and explicitly differentiates it from sibling tools by mentioning live position (get_vessel) and area-based search (get_vessels_in_radius). It uses specific verbs and resource names, leaving 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 provides explicit when-to-use and when-not-to-use guidance. It states 'Provide at least one search criterion' (a usage constraint), mentions the credit cost, and names alternatives for live position and area searches. This leaves no doubt about when this tool is appropriate.

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