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x402 AgentUtility D20 Ability Check Resolver
x402
x402 AgentUtility D20 Ability Check Resolver is a paid API for AI agents from x402.agentutility.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-20).
Resolves a d20 ability check, skill check, attack roll, or saving throw for tabletop RPGs, returning the roll total, success/failure against a DC, and natural-20/natural-1 flags.
Price / call$0.005
Success—
StatusUnknown
How this service works
Resolves a d20 ability check, skill check, attack roll, or saving throw for tabletop RPGs. Rolls a d20 with an optional modifier and advantage/disadvantage, compares to a DC, and reports total, success/failure, and natural-20 / natural-1. Seedable. Use it as a d20 check resolver API for any RPG.
Output
Returns the raw d20 die value, the final total (die + modifier), whether the total meets or exceeds the DC (success or failure), and boolean flags for natural-20 and natural-1 outcomes. If advantage or disadvantage was applied, both dice values may be included.
Example use cases
Combat attack roll resolution
“My fighter is attacking a goblin — roll a d20 with a +6 modifier against AC 13, with no advantage or disadvantage, and tell me if the attack hits or if I rolled a natural 20.”
Saving throw with disadvantage
“My wizard needs to make a Constitution saving throw against DC 12 with disadvantage and a +1 modifier — resolve the roll and tell me if they succeed or fail.”
Seeded skill check for replay
“Roll a Stealth check for my rogue with a +7 modifier against DC 15, no advantage or disadvantage, using seed 42 so we can reproduce the result — did they succeed?”
Technical details
Endpoint
POSThttps://x402.agentutility.ai/ability-check?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a verifiable, auditable, server-side d20 roll with optional modifier and advantage/disadvantage mechanics — especially for AI-driven TTRPG agents where client-side randomness is untrusted, or when you need seedable/reproducible rolls for GMing, testing, or dispute resolution. Prefer it over client-side dice rollers when you need canonical pass/fail adjudication against a DC in an automated workflow.
Side effects
- Invalid modifier type returns a 400 validation error
- DC value out of expected range may return an error
- Missing required fields (e.g. no DC provided) causes a 422 unprocessable entity
- Seed value conflicts or out-of-range inputs may return a 400 error
- Network timeout on the x402 payment layer before the roll is resolved
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"dc": 15,
"mode": "advantage",
"total": 20,
"success": true,
"modifier": 5,
"d20_rolls": [
15,
7
],
"natural_roll": 15,
"critical_failure": false,
"critical_success": false
}
}Tags
x402
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