list_countriesThe supported countries and their official currencies. Public, no key needed.
This tool declares no required parameters. Add optional parameters from the input schema as needed.
{
"id": 1,
"jsonrpc": "2.0",
"method": "tools/call",
"params": {
"arguments": {},
"name": "list_countries"
}
}| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, idempotent, non-destructive, and closed-world behavior. The description adds useful context beyond annotations by stating the endpoint is public and requires no API key, and it indicates the tool returns country/currency data. It does not mention rate limits or response shape, but given the annotations, the added auth context is meaningful.
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 description is two short sentences with no wasted words. It front-loads the core purpose and follows with authentication context, making it easy to scan.
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, annotation-rich, zero-parameter listing tool, the description covers what is returned and that no key is required. The only notable gap is that there is no output schema, so the exact response structure is not described, but the description is otherwise sufficient.
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 has zero parameters, so there is no parameter semantics burden. The baseline for a zero-parameter tool is 4, and the description does not introduce any confusing parameter-related claims.
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 specifies the resource clearly: supported countries and their official currencies. It is understandable without the schema, but it does not explicitly distinguish the tool from the sibling list_currencies, which likely overlaps on currency data.
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 description implies this tool is for listing supported countries and states that it is public with no key needed. However, it gives no explicit guidance on when to choose this tool over list_currencies or other sibling tools, and no exclusions or alternatives are named.
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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