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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new behavior: it discloses the fallback ('Returns a general list if the nationality has no curated page') and hints that results are curated, matching openWorldHint=false.

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?

Three sentences, zero filler: purpose first, trigger second, edge-case behavior last. Every sentence earns its place and the most important information is front-loaded.

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 correctly describes the return shape (destinations, key stats, FAQ) and the empty-curation fallback. For a one-parameter read tool this is nearly complete; only the nationality string format (e.g., country name vs. ISO code) is left unresolved.

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 coverage is 0% and the single parameter is undocumented in the schema, so the description must carry it. 'Citizens of a given country' clarifies that nationality means a country of citizenship rather than a person or visa type, which is meaningfully more than the bare 'nationality' string in the schema.

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 and resource: 'List destinations and a suggested visa pathway for citizens of a given country', plus the expected payload (4-6 destinations with stats and an FAQ). The nationality-scoped framing implicitly separates it from siblings like transita_compare_visas and transita_match_visas, but no sibling is named outright.

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?

'Use it when the person asks where they could move and only knows their citizenship' gives a clear situational trigger that distinguishes it from tools needing more input. No explicit exclusions or named alternatives, so it stops short of a 5.

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