Free sample: real output for Paris (75056) as of 2018-03-01, while a claim window was open. Same shape as catnat_lookup.
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": "catnat_example"
}
}| 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 burden and does disclose key behavior: the output is a static snapshot pinned to Paris (75056) as of 2018-03-01, not live data, and it is free of cost. It stops short of saying outright that no backend call occurs, which is the one fact an agent most needs.
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?
Two compact sentences, front-loaded with the most useful facts (free, fixed example, specific location and date). "while a claim window was open" is slightly cryptic but plausibly meaningful context for interpreting the sample data.
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-argument sample tool with no output schema, the description supplies what matters: it is free, it is a frozen snapshot, and its response shape matches catnat_lookup. Relying on the sibling's schema to define the return shape is a small completeness gap but a reasonable shortcut.
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 and the schema is an empty object at 100% coverage, so there is nothing for the description to disambiguate. Baseline 4 applies; the description correctly adds no parameter noise.
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?
"Free sample: real output for Paris (75056) as of 2018-03-01" makes clear this returns a fixed example payload, and the closing clause "Same shape as catnat_lookup" ties it directly to the sibling tool it mirrors. The only softness is that it never uses an explicit verb like "returns", leaving the action implied.
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?
"Free sample" hints at the use case (inspect output shape without spending a real lookup), but it never states when to call this instead of catnat_lookup or that it takes no arguments. The alternative is named only as a shape reference, not as a routing decision, so the guidance is implied rather than explicit.
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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