Free sample: the current #1 top-ranked signal, no payment. Full top-5 and 20-pair universe via the paid report/signals tools ($0.001/call).
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": "preview"
}
}| 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?
No annotations are present, so the description carries the full behavioral burden. It usefully discloses the limited scope (only the current #1 signal, not the full universe) and the cost behavior (free), but it does not explicitly describe the output format, potential side effects, or any access requirements. 'Free sample' implies read-only behavior but does not state it.
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-load the key fact ('Free sample') and then cover scope, cost, and alternatives without redundancy. Every phrase adds useful 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 no-parameter, no-output-schema preview tool, the description conveys the essential return value (current #1 top-ranked signal), its free cost, and where to get the fuller results. It leaves some ambiguity about what exactly a 'signal' contains, but the tool is simple enough that this is a minor gap.
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 and the input schema is empty with 100% coverage, so there are no parameter semantics for the description to clarify. The baseline of 4 is appropriate because no compensation is needed.
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 clearly defines the tool as providing a free sample of the current #1 top-ranked signal, which is a specific resource and action. It also distinguishes itself from siblings by contrasting the free single result with the paid full top-5 and 20-pair report/signals tools.
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 states when this tool is appropriate (free sample of the current #1 signal, no payment) and directs users needing more data to the paid report/signals tools. This gives an agent a clear selection heuristic between preview and the fuller sibling tools.
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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