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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds substantial behavioral context beyond those hints: it explains the Cyprus 60-day rule is flagged only when not 183+ resident elsewhere, that results include safe days left, leave-by dates, and a safe/warning/triggered rating, and that optional income enables tax-cost projection. It also hedges with 'Early-warning day math — not tax advice.' No contradiction with 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?

The description is dense but organized with numbered output categories, making complex information scannable. The disclaimer and supersession note are useful and short. It could be slightly more streamlined, but every sentence contributes meaningful guidance.

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?

For a complex multi-result tool, the description covers the main inputs, outputs, rating semantics, jurisdiction-specific logic, and alternatives. Since an output schema exists, the description does not need to enumerate every return field. The combination of detailed prose, schema, and annotations leaves little ambiguity about what the tool does and how to invoke it.

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 67%, so the description carries meaningful weight. It enriches 'stays' by framing it as a travel itinerary, and 'income' by explaining it enables tax-cost projection for at-risk countries. It does not explicitly describe 'referenceDate', but the schema already documents it as an optional 'as of' date defaulting to today. This is strong but not exhaustive.

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?

The description names a concrete verb ('returns') and a precise resource ('from one travel itinerary'), then enumerates three specific outputs: Schengen 90/180 status, per-country tax-residency risk, and tax-cost projection. It also explicitly distinguishes itself from sibling tools by saying it supersedes check_schengen, check_residency, and check_tax_residency_risk.

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 description gives direct routing guidance: 'Supersedes check_schengen / check_residency / check_tax_residency_risk (all still available).' This tells an agent this unified tool should be preferred over those alternatives while acknowledging they remain callable. That is explicit when-to-use guidance relative to siblings.

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