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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered, and the description adds genuinely new context: pricing ($0.002 USDC per successful call via x402), the fact that failed calls are not charged, and the caveat that individual licence numbers are not published. Only the return shape/pagination behavior is left implicit.

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?

Front-loaded with the resource and source, then query modes, then the important limitation and cost. Dense but each sentence carries information; the pricing clause is a bit longer than strictly needed but still earns its place.

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?

An output schema exists, so return values need no explanation, and the description still covers what data is available, the key data limitation (no licence numbers), the interpretation of a miss, accepted query modes, and payment mechanics. An agent has everything needed to call it and interpret the result.

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 description coverage is 100%, so q, limit, and state are already fully documented in the schema. The description restates the same facts (name part or filer code, state listing) without adding syntax, matching rules, or default behavior beyond what the schema says, so baseline 3 applies.

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?

States a specific verb ("Check") and resource ("US customs broker") against a named authoritative source, and enumerates the fields returned (filer code, broker name, city, state, phone, e-mail). This clearly separates it from sibling lookups like logistics_customs_cbp_manifest or logistics_us_cbp_cross_rulings.

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?

Explicitly lists the three query modes (by name, by 3-character filer code, or list a state), which tells the agent how to drive the tool. It also explains the negative case (a broker absent from the list holds no national permit), but names no alternative sibling tool or when-not-to-use condition.

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