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

Goes well beyond the readOnly/openWorld annotations by disclosing the paid model: $0.002 USDC per successful call via x402 on Base, Solana or Arc, with failed calls not charged — exactly the kind of cost/auth context annotations cannot convey. It also flags the jurisdictional limitation. It does not mention rate limits, table edition/currency, or result-set size.

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?

Three sentences, front-loaded with the resource and its scope, then the disambiguation, then cost. The cost sentence is long but each clause (price, currency, rails, failure policy) carries distinct information. Only the field enumeration slightly duplicates what the output schema likely covers.

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-value documentation is not required, and the payment mechanics — the main non-obvious risk for an autonomous caller — are fully covered. Remaining gap is minor: no mention of table version/recency or how partial name matches are resolved.

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% and the single param already documents both accepted forms and the 3–60 character bound. The description's "(e.g. 1203)" and "(e.g. gasoline)" merely restate the schema examples, adding no syntax or edge-case guidance (e.g. leading zeros, partial UN numbers). 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 resource (US hazardous materials table, 49 CFR 172.101) and enumerates the returned fields: UN number, proper shipping name, hazard class, packing group, labels, special provisions. It also draws an explicit boundary against the UN Model Regulations list, so an agent can distinguish this from a generic UN-list or placard tool.

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?

Gives concrete input forms for both accepted query styles ("1203" for a UN number, "gasoline" for a name fragment), which tells the agent how to invoke it. It scopes the tool as US DOT rather than the international UN list, but never names a sibling alternative or states a 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.