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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered without the description. Beyond that, the description contributes the domain rule being applied (the 6-month validity rule) and that a note is returned, but says nothing about how edge cases are judged (exact-boundary dates, expired passports) or what the note contains.

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 short sentences, front-loaded with the action and the rule that governs it; nothing is buried. The only waste is the unresolvable 'Returns: {note}' placeholder, which reads as an unfilled template slot rather than useful content.

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, deterministic check with an output schema present, the description covers what the tool does and the rule it applies, so an agent has enough to invoke it correctly. It is very slightly short of complete because the '{note}' placeholder suggests the return semantic was templated rather than described, though the output schema covers that 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?

Schema description coverage is 100% — both 'expiry_date' and 'travel_date' are documented with their YYYY-MM-DD format in the schema. The description adds no parameter-level meaning such as timezone assumptions or whether travel_date is departure or return. Per the rubric, 100% coverage sets the baseline at 3.

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 ('Check if passport is valid for travel') plus the governing rule ('6-month rule'), which is far more informative than the tautological name. It is clearly distinguishable from the hundreds of 'calculate_*' siblings since none other touches passport validity. The trailing template artifact ('Returns: {note}') slightly muddies an otherwise crisp statement.

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 agent can infer 'use this when planning international travel and you need to verify passport validity.' The only explicit pointer is a cross-reference to list_bundles for related 'voyage' calculators, which is a discovery hint rather than a when-to-use/when-not instruction or an alternative-tool comparison. No exclusions or prerequisites are stated.

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