roll_dice
Generate random dice rolls using standard dice notation to simulate probability outcomes for games, calculations, or decision-making scenarios.
Instructions
Roll the dice with the given notation
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| notation | Yes | ||
| num_rolls | No |
Input Schema (JSON Schema)
{
"properties": {
"notation": {
"title": "Notation",
"type": "string"
},
"num_rolls": {
"default": 1,
"title": "Num Rolls",
"type": "integer"
}
},
"required": [
"notation"
],
"type": "object"
}
Implementation Reference
- server.py:18-23 (handler)The main handler for the 'roll_dice' tool. It is registered using the @mcp.tool() decorator and executes the dice rolling logic by instantiating DiceRoller and returning its string representation.@mcp.tool() def roll_dice(notation: str, num_rolls: int = 1) -> str: """Roll the dice with the given notation""" roller = DiceRoller(notation, num_rolls) return str(roller)
- server.py:19-20 (schema)The function signature defines the input schema (notation: str, num_rolls: int=1) and output (str), with docstring for description. Used by FastMCP for tool schema.def roll_dice(notation: str, num_rolls: int = 1) -> str: """Roll the dice with the given notation"""
- server.py:18-18 (registration)The @mcp.tool() decorator registers the roll_dice function as an MCP tool.@mcp.tool()
- dice_roller.py:4-47 (helper)The DiceRoller class implements the core dice rolling functionality, parsing notation, rolling dice with optional keep highest, and formatting output used by the tool handler.class DiceRoller: def __init__(self, notation, num_rolls=1): self.notation = notation self.num_rolls = num_rolls self.dice_pattern = re.compile(r"(\d+)d(\d+)(k(\d+))?") def roll_dice(self): match = self.dice_pattern.match(self.notation) if not match: raise ValueError("Invalid dice notation") num_dice = int(match.group(1)) dice_sides = int(match.group(2)) keep = int(match.group(4)) if match.group(4) else num_dice rolls = [random.randint(1, dice_sides) for _ in range(num_dice)] rolls.sort(reverse=True) kept_rolls = rolls[:keep] return rolls, kept_rolls def roll_multiple(self): """Roll the dice multiple times according to num_rolls""" results = [] for _ in range(self.num_rolls): rolls, kept_rolls = self.roll_dice() results.append({ "rolls": rolls, "kept": kept_rolls, "total": sum(kept_rolls) }) return results def __str__(self): if self.num_rolls == 1: rolls, kept_rolls = self.roll_dice() return f"ROLLS: {', '.join(map(str, rolls))} -> RETURNS: {sum(kept_rolls)}" else: results = self.roll_multiple() result_strs = [] for i, result in enumerate(results, 1): result_strs.append(f"Roll {i}: ROLLS: {', '.join(map(str, result['rolls']))} -> RETURNS: {result['total']}") return "\n".join(result_strs)