x402-weblens-mcp

Position size & ATR stop ($0.002)

rugprobe_position_size

Calculate position size and stop-loss from account size, risk percentage, and ATR or price bars. Returns Wilder ATR, stop price, units, and position value.

Instructions

Position size and stop-loss from account risk: give price bars (high/low/close, oldest first) or an ATR plus entry, the account size and risk %. Returns Wilder ATR, stop price, units and position value. Math only, not financial advice. Costs $0.002 USDC.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "accountSize": "<accountSize>",
      "riskPct": "<riskPct>"
    },
    "name": "rugprobe_position_size"
  }
}

Input Schema

Name	Required	Description
`atr`	No	ATR, if you already have it (then also send entry)
`bars`	No	Price bars, oldest first
`side`	No
`entry`	No	Entry price (default: last close)
`period`	No	ATR period (default 14)
`riskPct`	Yes	Percent of the account to risk, e.g. 1
`multiplier`	No	Stop distance in ATRs (default 2)
`accountSize`	Yes	Account size

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.3.0Nov 12, 2026

TDQS

A3.9/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden and does well: it discloses that the call costs $0.002 USDC (a payment requirement an agent must know), that the tool is pure computation rather than advice, and precisely which values come back. It stops short of covering failure behavior — e.g. what happens when neither bars nor atr is supplied, or when fewer bars than the ATR period are provided.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

It is a single dense passage that is front-loaded with the purpose, then the inputs, then the outputs, then the cost — a sensible order with no filler. The middle clause stacking three input types into one breath reads slightly run-on, and the $0.002 cost appears in both title and description.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with no output schema and no annotations, the description compensates well by naming every returned quantity and disclosing the price. What is missing is modest but real: how the tool behaves when required inputs conflict or are insufficient (short bar series, missing atr without entry) and whether 'side' changes the outputs.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 88%, so field-level meaning is already documented, and the description largely restates it ('price bars (high/low/close, oldest first)', 'an ATR plus entry'). The one genuine addition is framing the two mutually exclusive input paths and tying outputs to inputs, but it adds no syntax, formats, or edge-case semantics beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states exactly what is computed — position size and stop-loss derived from account risk — and enumerates the return values (Wilder ATR, stop price, units, position value). No sibling in the catalog performs position sizing, so there is no ambiguity about which tool handles this, and an agent can select it without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied through the input modes: supply price bars, or an ATR plus entry, along with account size and risk %. There is no explicit statement of when this tool is the right choice versus alternatives, no prerequisites, and no when-not-to-use guidance. The 'Math only, not financial advice' line sets scope but is a disclaimer, not selection guidance.

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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