Every country in the Library with its code, its page and its as-of date.
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?
With no annotations, the description carries the full disclosure burden; it does confirm the call is a complete, unfiltered read and identifies the returned fields, which is real value since there is no output schema. It omits ordering, result size, and whether the 'as-of date' reflects a snapshot, leaving behavioral questions open for an agent that needs deterministic output.
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 no filler; the scope ('every country') leads and the returned attributes follow. Nothing can be trimmed 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 zero-parameter list tool with no output schema, the description is close to sufficient, but two returned fields are left undefined: 'page' (documentation URL? page reference?) and what the 'as-of date' means. An agent can call it correctly but cannot confidently predict what 'page' contains.
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 the baseline of 4 applies; there is no parameter meaning for the description to add or omit.
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 (every country in the Library) and enumerates what comes back (code, page, as-of date), so the enumeration intent is unmistakable. It is weaker only in that it never states the verb explicitly ('list') or contrasts itself with the sibling get_rulebook, though the resource difference makes confusion unlikely.
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 implied rather than stated: 'Every country' signals an unfiltered full-enumeration call, and with zero parameters there is no filtering choice for an agent to get wrong. No explicit when-to-use or when-not-to-use guidance is offered, and the sibling get_rulebook is not referenced.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.