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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description correctly focuses on other traits: alias normalization behavior and a citation constraint restricting domains to sorted.travel's place_url/source_url. This is meaningful added context beyond the annotations.

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 sentence, followed by naming convention, disclaimer, and citation rule. Every sentence adds a usable instruction, though the trailing citation rule reads more like response-handling guidance than tool selection and slightly pads the entry.

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, return values need not be explained, and the description covers naming, disclaimers, and citation sourcing. For a low-complexity read-only lookup this is nearly complete; only the user_visas code semantics live solely in the schema.

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 baseline is 3; the description adds value by stating that common aliases are accepted and normalized, which is not conveyed by the schema's per-field descriptions. The naming example overlaps the schema's own 'Use USA, not United States' notes.

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 ('Check') and resource ('visa requirements') plus the two defining inputs (passport country and destination country). No sibling covers visas, so an agent can select this tool unambiguously from the destination/weather/profile family.

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?

Provides clear usage context: how to phrase country inputs and an explicit caveat that output is 'planning context, not official immigration advice.' It does not name any alternative tool, but there is no competing visa sibling, so the caveat plus naming guidance is sufficient.

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