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

The description discloses the payment requirement (HTTP 402, x402 header, USDC on Base) which annotations do not cover. It also previews the output structure and the 'best passport per leg' behavior, adding substantial context beyond the annotations' readOnly/idempotent hints. 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 two sentences, the first quickly communicates the core evaluation scope and the second concisely explains the crucial payment flow. No filler; each clause adds distinct value, and the primary purpose is front-loaded before the cost implication.

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 tool with a rich input schema and an output schema, the description covers the essential context: scope, paid status, payment flow, and output structure. Combined with 100% schema coverage and the output schema, the description leaves little ambiguity for an agent to decide when 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?

The input schema already provides 100% coverage with detailed field descriptions, so the baseline is 3. The description adds meaningful high-level semantics, particularly 'best passport per leg', which explains how the tool optimizes the passports array across legs. This goes beyond the schema's raw field descriptions.

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 clearly states it evaluates a whole trip, enumerating specific inputs (multiple passports, documents, multi-leg itineraries with transit legs, dates, purpose) and outputs (structured why[], conditions, verification states). It explicitly differentiates from sibling tools by emphasizing the full-trip, multi-passport scope, making it distinct from a simple entry check.

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 sets a clear context: use this when you need a premium whole-trip evaluation with multiple passports and structured explanations. It does not explicitly name alternatives or state when not to use it, but the emphasis on 'whole trip' and 'one call' implicitly contrasts with simpler per-entry checks like check_entry_requirements.

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