who_euro_countriesList the countries and country groups covered by the WHO European Region Data Warehouse, with their codes. Country groups include the WHO European Region, EU members, CIS and others, and can be used directly as a country argument to get grouped values. Use to resolve a European country to the code WHO Europe data uses.
| Name | Required | Description | Default |
|---|---|---|---|
| query | No | Optional country name or code to look up. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover readOnly, idempotent, openWorld, and non-destructive hints. The description adds that country groups can be used as a country argument for grouped values, which is useful context beyond the schema, but it doesn't disclose response format or pagination. With annotations present, a 3 is appropriate.
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 with no fluff. The first sentence states the core purpose, the second elaborates on country groups, and the third gives usage direction. The second sentence is slightly dense but still earns its place.
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 read-only listing tool with one optional parameter and no output schema, the description covers what it returns (countries/groups with codes), how the results can be used, and the parameter's role. No critical information is missing for correct invocation.
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% for the single optional `query` parameter, and the schema already includes 'Optional country name or code to look up.' The description adds little beyond this, so it meets the baseline but doesn't elevate the parameter meaning.
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 states a specific verb and resource ('List the countries and country groups covered by the WHO European Region Data Warehouse') and clarifies the output includes codes. It also distinguishes itself from sibling WHO Europe tools by focusing on country resolution rather than datasets or measures.
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?
It explicitly says 'Use to resolve a European country to the code WHO Europe data uses,' giving a clear when-to-use scenario. It doesn't mention alternatives or when-not-to-use, but the use case is distinct enough from siblings to be identifiable.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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