Developer Tool · x402 · early usage

Chess Daily answer check — legally validates a complete UCI principal line against the…

Chess Daily answer check — legally validates a complete UCI principal line against the pinned daily puzzle.

by agent-arcade.use.x402atlas.com · discovered, not yet claimed by its owner · updated 2026-10-08

30d calls4

30d payers3

MethodPOST

Outputjson

Mirrored from Coinbase's public x402 Bazaar. The description is the provider's own text and has not been reviewed here; the payment requirements are copied as published.

What it does

Chess Daily answer check — legally validates a complete UCI principal line against the pinned daily puzzle.

Tags: chess-puzzle · chess-tactics · daily-chess · fen · uci · bazaar

Call contract

Method: POST
Input: json
Output: json
Last paid call: 2026-10-08

Input example from Bazaar metadata

{
  "answer": {
    "moves": [
      "d1h5",
      "h7h6",
      "h5c5"
    ]
  },
  "challenge_id": "sha256:50697ebea7b2cc5947da85e12fe2069f49983c4ba3d206b09540d80733c0153a",
  "date": "2026-07-01",
  "difficulty": "normal",
  "generation_version": "v1"
}

Output example

{
  "challenge_id": "sha256:50697ebea7b2cc5947da85e12fe2069f49983c4ba3d206b09540d80733c0153a",
  "correct": true,
  "feedback": {
    "first_invalid_move": null,
    "message": "complete legal principal line",
    "required_moves": 3,
    "submitted_moves": 3
  },
  "game": "chess",
  "proof": {
    "normalized_line": [
      "d1h5",
      "h7h6",
      "h5c5"
    ]
  },
  "score": 100,
  "valid": true
}

Use with an agent

Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
Inspect. Fetch /resources/28465.json for the price and payment options.
Pay. Call GET https://agent-arcade.use.x402atlas.com/chess/check. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
Execute. The provider returns 200 with the data. Agent Bazaar is not in the request path and never sees your payment.

For humans

You don't need an account or an API key; you need a wallet holding a small amount of USDC on Base, Polygon, Arbitrum One, Solana, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price: $0.005 / request
Protocol: x402 v2
Auth: No account or API key. Pay per request.
Networks: Base, Polygon, Arbitrum One, Solana
Demand: 4 calls · 3 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

Scheme	Network	Asset	Amount	Pay to	Timeout
exact	Base eip155:8453	USDC	$0.005	0x8C128f1Ee62Bb5e47867CfbAe2ad89be325Df1b2	300s
exact	Polygon eip155:137	USDC	$0.005	0x8C128f1Ee62Bb5e47867CfbAe2ad89be325Df1b2	300s
exact	Arbitrum One eip155:42161	USDC	$0.005	0x8C128f1Ee62Bb5e47867CfbAe2ad89be325Df1b2	300s
exact	Solana solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp	USDC	$0.005	ASt6xvRyQ7ntERsmcYVMdLqZvz1GEN8Fzexzq62tXrNQ	300s

accepts[] (raw JSON)

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0x8C128f1Ee62Bb5e47867CfbAe2ad89be325Df1b2",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "5000",
    "amountUsd": 0.005,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:137",
    "payTo": "0x8C128f1Ee62Bb5e47867CfbAe2ad89be325Df1b2",
    "asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
    "amount": "5000",
    "amountUsd": 0.005,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:42161",
    "payTo": "0x8C128f1Ee62Bb5e47867CfbAe2ad89be325Df1b2",
    "asset": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
    "amount": "5000",
    "amountUsd": 0.005,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "payTo": "ASt6xvRyQ7ntERsmcYVMdLqZvz1GEN8Fzexzq62tXrNQ",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": "5000",
    "amountUsd": 0.005,
    "maxTimeoutSeconds": 300
  }
]

Schemas

Output schema (JSON Schema)

{
  "properties": {
    "example": {
      "additionalProperties": false,
      "description": "Chess Daily answer-check legality and principal-line verdict.",
      "properties": {
        "challenge_id": {
          "description": "Checked Chess Daily challenge identity.",
          "type": "string"
        },
        "correct": {
          "description": "Whether the complete Chess Daily principal line matches.",
          "type": "boolean"
        },
        "feedback": {
          "additionalProperties": false,
          "description": "Chess Daily move legality and line-length feedback.",
          "properties": {
            "first_invalid_move": {
              "type": [
                "integer",
                "null"
              ]
            },
            "message": {
              "type": "string"
            },
            "required_moves": {
              "type": "integer"
            },
            "submitted_moves": {
              "type": "integer"
            }
          },
          "required": [
            "message",
            "first_invalid_move",
            "submitted_moves",
            "required_moves"
          ],
          "type": "object"
        },
        "game": {
          "description": "Chess Daily game identity.",
          "enum": [
            "chess"
          ],
          "type": "string"
        },
        "proof": {
          "additionalProperties": false,
          "description": "Present only after a correct Chess Daily answer.",
          "properties": {
            "normalized_line": {
              "items": {
                "type": "string"
              },
              "type": "array"
            }
          },
          "required": [
            "normalized_line"
          ],
          "type": "object"
        },
        "score": {
          "description": "Informational Chess Daily score: 100 when correct, otherwise 0.",
          "type": "integer"
        },
        "valid": {
          "description": "Whether every submitted Chess Daily move is legal.",
          "type": "boolean"
        }
      },
      "required": [
        "challenge_id",
        "game",
        "valid",
        "correct",
        "score",
        "feedback"
      ],
      "type": "object"
    },
    "type": {
      "type": "string"
    }
  },
  "required": [
    "type"
  ],
  "type": "object"
}

Example shape — generated from the schema, not a captured live response

{
  "example": {
    "challenge_id": "string",
    "correct": true,
    "feedback": {
      "first_invalid_move": 0,
      "message": "string",
      "required_moves": 0,
      "submitted_moves": 0
    },
    "game": "chess",
    "proof": {
      "normalized_line": [
        "string"
      ]
    },
    "score": 0,
    "valid": true
  },
  "type": "string"
}

Examples

curl

curl "https://agent-arcade.use.x402atlas.com/chess/check"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

JavaScript

const res = await fetch("https://agent-arcade.use.x402atlas.com/chess/check");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

Python

import httpx
res = httpx.get("https://agent-arcade.use.x402atlas.com/chess/check")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header

Details

Provider: agent-arcade.use.x402atlas.com
Endpoint: https://agent-arcade.use.x402atlas.com/chess/check
Machine-readable: /resources/28465.json