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

Beyond the readOnly/idempotent/openWorld annotations, the description discloses that every rule carries a verbatim official quote and source link, and warns that a country without data returns an error which must not be reported as 'nothing is restricted' — a genuine failure-mode trap an agent would otherwise fall into. It does not cover rule freshness or caching, so not a 5.

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?

Purpose is front-loaded in the first clause, the error caution is second, and the use case closes it. The final sentence partly restates the topic list already given in sentence one, which is mild redundancy but keeps the text scannable.

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?

With an output schema present and full parameter documentation, the description carries only the burden of scope and failure semantics, which it does well. It leaves locale/language behavior to the schema, which is acceptable given the parameter description covers it explicitly.

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 schema already explains country_code, from, and locale in detail (including the 'no customs inside the EU' nuance). The description only lightly gestures at the optional origin country ('optionally from a given country') and adds nothing on locale, so it earns the baseline rather than more.

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 and resource ('customs rules when driving into a country') and enumerates the exact scope: food bans, cash declaration, alcohol/tobacco limits, goods value, fuel canister. This is clearly distinguishable from siblings like get_vehicle_import_rules or check_visa_rules without opening a schema.

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 closing sentence gives clear usage framing ('what you may bring in by car: alcohol, tobacco, cash, meat and other food, goods limits') and the error warning sets an expectation for missing-data cases. It stops short of naming an alternative sibling or a when-not-to-use condition, so it doesn't reach the top band.

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