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

Annotations already indicate a safe, read-only, idempotent operation, but the description adds critical behavioral context beyond that: payment requirements ('PAID: $0.03/call via x402'), failure behavior ('Without payment, returns 402 with payment instructions'), and a clear return format ('Array of { origin, destination, mode, container_types, icd_code }'). This is valuable transparency not present in the schema or annotations alone.

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 4 sentences long, each with a distinct purpose: purpose statement, usage example, payment/pricing note, and return type. No filler or redundant phrasing. It is front-loaded with the core action, then provides necessary context, making it both 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?

Despite having 6 parameters and no output schema, the description covers all essential context: it states the tool's scope, includes a realistic example, explains payment and error behavior, and describes the return shape. It also clarifies how it differs from two sibling tools. This is a complete and self-contained guide for the agent.

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?

Input schema covers all 6 parameters with complete descriptions (100% coverage), so baseline is 3. The description adds a concrete usage example—'search "ahmedabad" to find routes from Nhava Sheva to Ahmedabad via Maersk'—that clarifies how the keyword parameter is intended to be used. While the schema already defines each field, the example provides practical meaning, justifying a 4 rather than a 3.

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 starts with 'Search for available inland transport routes (road/rail haulage) from port to inland destinations for a specific carrier,' which precisely states the action, resource, and scope. It also distinguishes itself from siblings by explicitly pointing to shippingrates_inland_haulage for rate quotes and shippingrates_inland_compare for comparisons, making the purpose unmistakable.

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 gives direct guidance: 'Use this to discover what haulage routes a carrier offers in a country.' It further clarifies exclusions: 'For actual haulage rate quotes, use shippingrates_inland_haulage. For cross-carrier rate comparison, use shippingrates_inland_compare.' This is explicit when-to-use and alternative tooling, meeting the highest bar.

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