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

No annotations are provided, so the description carries the full disclosure burden. It does usefully name the outcome states (compliant/warning/over plus advice), but says nothing about read-only nature, date inclusivity rules, or how existing stays are counted beyond what the schema states.

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, front-loaded with the core question, no filler. The result states are appended compactly rather than padded into prose.

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?

There is no output schema, and the description compensates by naming the return states, which is the most important missing piece. It stops short of explaining what distinguishes 'warning' from 'over', but combined with the fully-described schema this is nearly sufficient to call the tool correctly.

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 the nested trip objects are already documented inline, so the baseline is 3. The description adds only the framing that the check is against 'existing stays' and concerns a single planned trip, not per-parameter detail.

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 (one planned trip) plus the evaluation context (on top of existing Schengen stays). The emphasis on 'ONE' cleanly separates it from calculate_stay and explain_90_180_rule, so an agent can route without opening a schema.

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 usage context (verifying a single prospective trip against prior stays), but never names the sibling tools or states when to prefer calculate_stay or explain_90_180_rule instead. Usage is inferable rather than stated.

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