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

Annotations already declare readOnlyHint=true / destructiveHint=false, so the safety profile is covered. Beyond that, the description adds real context: the size of the dataset (240+), the fields attached to each entry (currency codes, symbols, flags, phone codes, price groups) and the fact they come from 'live platform settings' (i.e., data may change). It is silent on pagination behavior despite the limit parameter.

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?

A single front-loaded sentence with the verb first and no filler; the trailing field list is doing work by previewing the payload. Nothing could be removed without losing information.

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 simple, read-only, two-optional-parameter tool, the description covers purpose and the shape of the returned records, which matters because there is no output schema. Only pagination/limit interaction and any search-matching caveats remain unaddressed, and those are minor for this complexity level.

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%, including the query field's accepted search axes and an example, so the schema already carries the parameter burden. The description echoes the search concept but adds no syntax, matching rules, or default/limit behavior beyond what the schema states. Baseline 3 is appropriate.

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 pairs a specific verb ('Search') with a specific resource ('240+ supported destination countries') and enumerates the data carried on each result, so the agent knows this is a catalog/read tool rather than a lookup of the user's own region. It does not explicitly contrast itself with region.get_current / region.set_current, but the scope is unambiguous.

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: calling it a search over 'supported destination countries' hints at discovery/validation use cases, but there is no statement of when to prefer this over region.get_current or the address.* tools, and no prerequisites or exclusions are given. Minimum viable guidance, nothing more.

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