Dice Rolling Skill Definition

Dice Rolling Skill

When to Use This Skill

Activate this skill when users:

Ask to roll dice (e.g., “roll 2d6”, “roll for damage”)
Need D&D 5E mechanics (advantage, disadvantage, ability scores)
Want game-specific rolls (Blades in the Dark, Daggerheart, PbtA, Root RPG, Salvage Union)
Need probability simulations or random number generation
Ask about dice notation syntax

Quick Notation Reference

RANDSUM uses an extended dice notation system. All notation is case-insensitive.

Basic Syntax: NdS where N = quantity, S = sides

Notation	Description	Example
`2d6`	Roll 2 six-sided dice	Standard damage roll
`1d20+5`	Roll d20, add 5	Attack roll with modifier
`4d6L`	Roll 4d6, drop lowest	D&D ability score generation
`2d20L`	Roll 2d20, drop lowest	Advantage (keep highest)
`2d20H`	Roll 2d20, drop highest	Disadvantage (keep lowest)
`3d6!`	Exploding dice	Reroll and add on max result
`4d6R{1}`	Reroll 1s	Avoid minimum results
`4d20U`	Unique results only	No duplicate values
`4d20C{>18}`	Cap values over 18 to 18	Limit maximum results

Multiple dice groups: 1d20+2d6+3 (attack plus damage), 2d12-1d6

For complete notation documentation, see references/NOTATION.md.

Game System Support

See references/GAME_SYSTEMS.md for detailed mechanics.

D&D 5E: Advantage 2d20L, Disadvantage 2d20H, Ability scores 4d6L
Blades in the Dark: d6 pools, keep highest; 6 = success, 4-5 = partial, 1-3 = failure
Daggerheart: 2d12 Hope/Fear dice
PbtA / Root RPG: 2d6 + stat; 10+ strong hit, 7-9 weak hit, 6- miss
Salvage Union: d20 roll-under; lower is better

Implementation Options

Option 1: MCP Server (Recommended for AI Agents)

{
  "mcpServers": {
    "randsum": {
      "command": "npx",
      "args": ["-y", "@randsum/mcp@latest"]
    }
  }
}

Available MCP tools: roll, validate-notation, try-roll, analyze, game-roll, batch-roll, compare, count-successes, preset.

Option 2: CLI

npx @randsum/roller "4d6L"

Option 3: Programmatic (TypeScript/JavaScript)

roll() accepts a number (sides for 1 die), a notation string, an options object, or multiple arguments:

import { roll } from "@randsum/roller"

// Number: 1 die with that many sides
roll(20) // 1d20

// Notation string
roll("2d6+3")

// Options object (same as 2d6+3)
roll({ sides: 6, quantity: 2, modifiers: { plus: 3 } })

// Multiple arguments: combined total
roll("1d20", "2d6", "+5") // attack + damage + modifier

const result = roll("2d6+3")
console.log(result.total) // Sum of dice + modifiers
console.log(result.rolls) // Original rolls
console.log(result.result) // After modifiers applied

Best Practices

Always explain rolls: When rolling dice, explain what the notation means
Show intermediate results: Display raw rolls before modifiers
Match the game system: Use appropriate mechanics for the user’s game
Validate first: For complex notation, validate before rolling
Provide context: Explain what success/failure means in the game context

Example Interactions

D&D Ability Score

User: “Roll for my D&D character’s strength score”

Response: Rolling 4d6L (4d6, drop lowest) for ability score generation…

Raw rolls: [4, 3, 5, 2]
Dropped: 2 (lowest)
Total: 12 (4 + 3 + 5)

Attack with Advantage

User: “I attack with advantage and my +7 modifier”

Response: Rolling 2d20L+7 (advantage = roll 2d20, keep highest)…

Raw rolls: [14, 8]
Kept: 14 (dropped 8)
Total: 21 (14 + 7)

Blades Action

User: “Roll a Blades action with 3 dice”

Response: Rolling 3d6 for Blades in the Dark action…

Results: [4, 6, 2]
Highest: 6 = Full Success!