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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description's job is to add context — and it does, disclosing the batch capacity (up to 10 passports) and the aggregate output ('the tightest leg of the route'). It does not explain what the weight parameter does to the returned rules, which is a minor omission.

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?

A single front-loaded sentence that packs scope, batch capacity, and the extra aggregate output with no filler. Every clause 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?

With no output schema, the description usefully previews the return (rules per country plus the tightest leg). It leaves a small gap in not clarifying why a vehicle-weight parameter exists on a visa-rules tool, but otherwise an agent has enough to call it correctly.

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 the schema already documents countries (up to 12), passports (up to 10), and the weight enum. The description reinforces the passport count but adds no syntax or format detail beyond the schema, and never mentions the weight parameter — baseline 3 is appropriate.

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 (visa rules) with a clear scope modifier (for every country of a route, in one call), which distinguishes it from the sibling check_visa_rules that presumably handles a single country. The differentiation is implicit rather than naming the sibling, so it falls just short of a 5.

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 phrase 'for every country of a route in one call' implies the usage context (multi-country trip planning) and implies the batching advantage over a per-country call, but there is no explicit when-to-use statement, no exclusions, and no named alternative among the many siblings.

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