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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is fully covered and the description only needs to add interpretive context. It does add one useful clarification (that returned times measure listing freshness, not seller uptime or booking success), which prevents misread results, but adds nothing about latency, caching, or per-country coverage limits beyond that single caveat.

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 short sentences: trigger first, return value second, disambiguation last. Every sentence carries a distinct piece of information and none repeats the title or annotations.

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 zero-parameter, read-only diagnostic with an output schema and rich annotations, the description covers what it returns, when to reach for it, and what it must not be mistaken for. Nothing needed to call it correctly is absent.

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 tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline is 4. The description adds nothing misleading about invocation.

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 and output: "Returns the latest snapshot time for each country." It implicitly separates itself from search_* siblings via the "when a search fails" framing and the explicit disclaimer that it is not uptime or booking-success data, though no sibling tool is ever named.

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 trigger condition is explicit and actionable: "Use this when a search fails or returns nothing unexpectedly." It also excludes a plausible misreading ("not a seller uptime or booking success measurement"), but it never names a concrete alternative tool to call instead, so the routing to siblings remains implicit.

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