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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds crucial context beyond those hints: it discloses that optional operational attributes (GPS, rail, operator, capacity) remain null unless certified by a separate source, and it details the payment requirement: 'PAID: $0.02/call via x402... Without payment, returns 402 with payment instructions.' It also explains the response shape ('Returns the existing facility response shape...'). This provides rich behavioral insight beyond the 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 organized into three clear paragraphs: purpose, usage context, payment, and return shape. Every sentence adds value without redundancy. It front-loads the primary action and then covers crucial operational details (payment and null attributes) in an efficient, scannable structure.

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 tool has no output schema, but the description compensates by explaining the response shape: 'Returns the existing facility response shape, with certified code/name/type and null for unsupported optional attributes.' It also covers the payment failure mode (402), the source (official ICEGATE), and the limitation on optional data. This is complete for a directory lookup tool, though a bit more detail on the response fields would be ideal.

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 individual descriptions, so the baseline is 3. The description adds meaningful context by stating that the current edition does not assert GPS, rail, operator, or capacity data, which clarifies how the rail_connected filter and output fields behave. It also clarifies that optional operational attributes will be null, not simply absent or unknown.

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 opens with a specific action: 'Search India's current official ICEGATE Inland Container Depot (ICD) and Container Freight Station (CFS) directory' and clarifies the search keys: code, name, and type. This clearly distinguishes the tool as a facility directory lookup compared to sibling tools like shippingrates_inland_search or shippingrates_cfs_tariffs.

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 states the intended use: 'Use this to resolve an official ICEGATE ICD/CFS code or facility name.' It implies that this tool is for validated, official directory lookups and not for unverified operational attributes. However, it does not explicitly contrast with alternative sibling tools or list exclusions for when not to use.

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