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

Annotations already cover the safety profile (readOnlyHint true, destructiveHint false, openWorldHint false), yet the description still adds real behavior: figures carry sources, values are in AUD or GBP, and uncovered places respond by saying so and listing covered places in that country. The remaining gap is response size/format, which matters for an enumeration this broad with no output schema.

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 resource and purpose are front-loaded in the first clause, and the long middle enumeration is dense but each item corresponds to a real returned data class. It is one block of prose rather than a list, which costs a little scannability, but there is no filler sentence.

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?

With no output schema, the description carries the full burden of describing return values and it does so field by field, plus currency, sourcing and the not-covered fallback. For a two-parameter read-only lookup, nothing an agent needs in order to call it and interpret the result 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 coverage is 100%, so the enum and the AU default are already documented, giving a baseline of 3. The description adds meaning on top by tying homeCountry to concrete outcomes (the visa for that home country and the AUD/GBP currency of the figures) and by signaling that 'place' spans town, island or country.

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 names a specific resource (checked facts for one destination) and enumerates exactly what is included: daily costs, transport and taxi prices, tourist tax, best months, visa, sights and a sample trip total. That enumeration also separates it from narrower siblings such as best_time_to_visit and check_entry_requirements, which cover only slices of this bundle.

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 implied — fetch this when you want a consolidated cost/visa/sights picture for a place — and the closing note 'Read only; no booking or search is made' usefully rules out a booking workflow. However, no sibling is ever named, so an agent is not told when to prefer best_time_to_visit, check_entry_requirements or get_day_plan over this broader tool.

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