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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open world). The description adds real value beyond that: each rule returns a verbatim official quote and source link, and a country with no data returns an error that must not be reported as 'nothing is restricted.' This is a meaningful failure-mode disclosure not present in the structured fields.

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 tightly packed sentences, front-loaded with the core resource and its covered domains, then return content, then the error caveat. No filler or repetition.

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 no output schema, the description carries the burden of describing returns and does so (verbatim quotes, source links) plus error semantics. It is nearly complete; only minor specifics such as locale effect on summaries or result pagination are left implicit.

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 all three params (from, locale, country_code) are already documented with format and semantics (ISO codes, EU exemption, supported locales). The description only echoes 'optionally from a given country,' adding no syntax or semantics beyond the schema — baseline 3.

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+resource (customs rules when driving into a country) and enumerates the concrete domains covered: food bans, cash declaration, alcohol/tobacco limits, goods value, fuel canister. This clearly separates it from siblings like get_vehicle_import_rules or get_route_visa_rules, which concern different regulatory areas.

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?

Frames the use case ('when driving into a country') and notes the optional origin country matters for EU-internal travel and origin-based exemptions. It gives clear context but stops short of naming when to prefer a sibling tool or an explicit boundary versus get_vehicle_import_rules.

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