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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful context beyond that: the classification is informational and may change, so results should not be treated as authoritative. It stops short of noting that the answer is a point-in-time snapshot without dates or that it doesn't cover permitted stay length.

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?

Two sentences, zero waste, with the classification enumeration front-loaded so the agent knows the return categories before reading the caveat. Nothing is padded or repeated.

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 one-parameter, read-only lookup with full schema coverage and annotations, the description supplies the missing pieces: what the output categories mean and a reliability caveat. It is close to complete, with only the absence of guidance relative to the day-counting siblings as a minor gap.

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 single parameter is fully documented in the schema (100% coverage), including accepted two-letter ISO codes and country names. The description adds nothing beyond that about the parameter, so the baseline 3 for high schema coverage applies.

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 (check) and resource (project's country classification) and enumerates the three possible classifications, which tells the agent exactly what answer shape to expect. It is clearly distinguishable from the sibling tools schengen_check_days and schengen_earliest_reentry, which deal with stay duration and reentry, not classification.

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?

Usage is only implied: the reader infers this is a per-nationality informational lookup, but no when-to-use condition, prerequisite, or comparison against the schengen_* siblings is given. The closing 'verify current entry rules with official authorities' hints at its role but doesn't route the agent to an alternative tool.

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