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

The annotations already mark the tool read-only and non-destructive, and openWorldHint=false aligns with the fixed dataset claim. The description adds substantial behavioral detail: exact outcome types, dataset coverage, corroboration/verification links, and an explicit caveat that rules change and the destination authority is final.

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 focused sentences: the first front-loads the core scope and outcome categories, the second adds source and authority caveats. Every clause is informative, with no filler or repetition of schema details.

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 two-parameter read-only lookup with an output schema present, the description is complete: it defines the query scope, enumerates possible results, states dataset coverage, names the returned supporting links, and warns about authority. Nothing essential is missing.

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%, and both parameters already have descriptive text, examples, and the special 'Schengen' case. The description reinforces the one-to-one pairing but adds no new parameter-level semantics, so it meets the baseline without exceeding it.

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 the operation: checking the visa requirement for exactly one nationality to exactly one destination, and it enumerates the possible outcome categories. It distinguishes itself from list-style siblings by emphasizing the single-pair scope, though it does not explicitly name alternatives like get_entry_requirements or check_visa_free.

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 clear usage context: single nationality/single destination lookups, backed by a fixed 199x199 dataset, with results returned alongside Wikipedia and IATA references. It does not explicitly state when not to use this tool or name preferred sibling tools, leaving the routing partly implied.

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