2d6-mcp-task-resolution

name: 2d6-mcp-task-resolution description: Dice rolling, effect margins, difficulty modifiers, boon/bane for the 2d6mcp MCP server.

2D6 MCP Task Resolution

You resolve tasks using system-appropriate dice mechanics. The server supports three core resolution systems: 2d6 (OGL/DW), d20 (5E/Orcus), and d100 (BRP/CoC/Darkmaster).

2d6 Resolution (OGL, Dungeon World)

Use the 2d6 ± modifier vs. target number mechanic. The standard difficulty target is 8+.

Standard Check

roll_2d6(modifier, target_number)

• modifier: Integer from skill ranks, characteristic bonus, difficulty, or circumstance
• target_number: Typically 8 for an average task (6 = easy, 10 = difficult, 12 = very difficult, 14 = formidable)

Interpreting Results

The tool returns:

• dice: Individual die results
• total: Sum of dice + modifier
• effect: Total minus target number

Effect Margins

Always report the margin and interpret it narratively. An exceptional success warrants significant additional benefit. An exceptional failure warrants a significant complication.

Difficulty Modifiers

Apply these as adjustments to the modifier, not the target:

Boon and Bane

When circumstances are unusually favourable or unfavourable, roll 3d6 and keep the highest (boon) or lowest (bane) two:

• Boon: Roll roll_custom("3d6"), take the two highest dice + modifier
• Bane: Roll roll_custom("3d6"), take the two lowest dice + modifier

Inspect individual dice from the custom roll to apply boon/bane logic manually.

d20 Resolution (5E-Compatible, Orcus, OSE)

Use the d20 + modifier vs. target number mechanic. The target is typically Armor Class (AC) or Difficulty Class (DC).

Standard Check

roll_d20(modifier, target, advantage, disadvantage)

• modifier: Attack bonus, ability modifier, or proficiency bonus
• target: Armor Class or Difficulty Class (optional — omitting returns a raw roll)
• advantage: If true, roll 2d20, use the higher result
• disadvantage: If true, roll 2d20, use the lower result
• Advantage + disadvantage on the same roll cancel — roll 1d20 normally

Interpreting Results

The tool returns:

• dice: Individual d20 result(s) — 1 die for normal, 2 dice for advantage/disadvantage
• total: Effective die result + modifier
• hit: true if total ≥ target (or natural 20), null if no target given
• critical: true if natural 20 (CRITICAL HIT — auto-hit + double damage dice)
• fumble: true if natural 1 (FUMBLE — auto-miss)

Advantage/Disadvantage Rules

• Multiple sources of advantage don't stack; multiple sources of disadvantage don't stack
• Advantage + disadvantage on the same roll cancel each other out
• When rerolling with advantage/disadvantage, reroll only one of the two dice
• Heroic Inspiration or similar reroll abilities interact: choose which die to reroll

d100 / Percentile Resolution (BRP, Call of Cthulhu, Darkmaster, Pendragon)

Use the d100 roll-under mechanic. Roll ≤ target to succeed. Lower rolls are better.

Standard Check

roll_percentile(target)

• target: The percentile chance of success (e.g., 45 for a 45% skill, 60 for DEX×5)
• Omitting target returns a raw percentile roll with no success/failure comparison

Interpreting Results

The tool returns:

• tens: The tens die (0-9)
• ones: The ones die (0-9)
• total: Combined result (1-100, where 00 = 100)
• success: true if total ≤ target, null if no target
• critical: true if total ≤ 5% of target (exceptional success)
• fumble: true if total ≥ 96 (and the roll is a failure)

Critical Success / Fumble Thresholds

• Critical: Roll ≤ floor(target × 0.05). Example: 50% skill → 01-02 is critical.
• Fumble: Roll 96-100 on a failed check.
• Critical successes and fumbles warrant dramatic narrative resolution.

Damage Rolls

Use roll_damage for weapon damage with type labels:

roll_damage("1d8 piercing")
roll_damage("2d6+3 fire")
roll_damage("4d6 bludgeoning")
roll_damage("1d4-1 slashing")

Returns: individual dice, modifier, total damage, damage type, and description.

Time Frames