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

Annotations already mark readOnly, idempotent, and non-destructive. The description adds key behavioral context: the paid $0.03/call requirement via x402, the 402 response when unpaid, and the return format. No contradiction with annotations.

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 front-loaded and compact, with clear sections for usage, alternatives, payment, and return format. Minor redundancy between 'Returns route options...' and 'Returns: Array of...' but no wasted sentences.

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 no output schema, the description explicitly defines the return array shape { origin, destination, mode, container_types, icd_code }. It also covers payment/error behavior and lists sibling alternatives, making it sufficient for a 6-parameter tool with 100% schema coverage.

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 coverage is 100%, so the baseline is 3. The description adds real-world usage context: the 'ahmedabad' example showing how the keyword maps to a route from Nhava Sheva, and the expected route fields (ICD/CFS codes, container types). This goes beyond the schema by illustrating query behavior.

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 a specific verb+resource: 'Search for available inland transport routes (road/rail haulage) from port to inland destinations for a specific carrier.' It clearly differentiates from sibling tools by naming shippingrates_inland_haulage and shippingrates_inland_compare for quote and comparison.

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?

'Use this to discover what haulage routes a carrier offers in a country... For actual haulage rate quotes, use shippingrates_inland_haulage. For cross-carrier rate comparison, use shippingrates_inland_compare.' This explicitly states when to use the tool and names alternatives.

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