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

Annotations already establish readOnly and non-destructive behavior Mendation. The description adds meaningful behavioral context beyond that: it cites the Passport Index dataset, the 199-passport coverage, the 'where published' caveat on stay days, and the 'verify before travel' warning. This is useful and non-contradictory.

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 front-loaded with the core purpose and then enumerates the returning groupings plus the source and caveat. It is longer than strictly minimal, but every included detail serves the invoking agent, and nothing is redundant filler.

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?

Given the presence of an output schema and annotations, the description sufficiently covers the tool's scope, data provenance, grouping behavior, and caution about verification. It does not explain pagination or error behavior, but those are not materially needed for this simple list operation.

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 schema already documents both from_nationality and group. The description reinforces that destinations are per one nationality and grouped, but it adds no new semantic details over the parameter 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 uses a specific verb ('list') and a precise resource: all destinations for a single nationality, grouped by requirement. It also enumerates the exact groupings and includes counts and a mobility total, making it clearly distinct from sibling tools like check_visa_free or check_visa_requirement.

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 implies the use case: a comprehensive overview for one nationality, rather than a specific single-country check. However, it never explicitly contrasts itself with alternatives such as check_visa_free, check_visa_requirement, or get_entry_requirements, nor gives when-not-to-use guidance.

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