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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the bar is lower, and the description still adds a genuinely useful behavior: a country without a supportable rule returns nothing rather than a guess. It also names the returned data points, which is context beyond the safety hints.

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?

Two sentences, front-loaded with the scope and the return contents, and the no-guess fallback behavior closes it. Every clause carries information.

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 the description needn't enumerate return structure, and it still sketches the returned facts and the empty-result case. Only the relationship to neighboring customs/visa tools is left unaddressed.

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% and both parameters (country formats, locale enum) are fully documented in the schema, so the baseline of 3 applies. The description adds no parameter-specific meaning such as accepted country identifier forms or locale behavior.

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 and scope: temporary admission rules for a foreign-plated vehicle in one country, and enumerates the facts returned (allowed days, per entry or per window, carnet, green card). This is clearly distinguishable from siblings like get_customs_rules or check_visa_rules without opening any 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 one-country scoping and the field list imply when this tool is the right one, but no sibling is named and there is no explicit when-not guidance (e.g. difference from get_customs_rules). Usage is inferred rather than directed.

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