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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description still adds real value beyond that: prices are 'official snapshot' data (implying point-in-time values), results come back sorted by largest gap, gaps are explicitly not savings, and requests live in the Qrrier app.

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?

Three sentences, front-loaded with the purpose before the parameter requirements, with no filler. The trailing note about requests being posted in the Qrrier app is slightly tangential but functions as a useful pointer to a sibling.

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?

An output schema exists, yet the description still summarizes the return payload (local prices, USD conversions, gap, sources, FX dates, sort order), which is bonus clarity rather than filler. Combined with full parameter naming and the freshness/savings caveats, an agent has nearly everything needed to call it correctly; only sibling disambiguation 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 description coverage is 0%, so the description carries the full burden and largely meets it: it specifies that origin_country and destination_country accept country names or ISO codes and that item is an optional filter. Only the empty-string default of item and any input length/format constraints are left unexplained.

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 (compare official snapshot prices) plus an explicit scope (any origin-to-destination route) with a concrete example (US to Brazil). It does not, however, differentiate itself from the similarly named sibling price_gap_lookup, so an agent facing both would need to open the schemas to choose.

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 definition gives clear invocation prerequisites (origin_country and destination_country are required, item is an optional filter) and a qualifying caveat ('Gaps are not guaranteed savings'). What it lacks is when-to-use versus when-not guidance, particularly against price_gap_lookup, which on name alone appears to cover adjacent territory.

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