# Agent Arcade: Chess Check Validator

> Agent Arcade: Chess Check Validator is a paid API for AI agents from agent-arcade.use.x402atlas.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Validates a submitted sequence of chess moves as a correct solution to a check puzzle, scoring and providing feedback on move legality and completeness

## Facts

- Endpoint: POST https://agent-arcade.use.x402atlas.com/chess/check
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-arcade-chess-check-validator-b5783484
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_JKqDc1wZT96aalvD-Qw9E

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability agent-arcade-chess-check-validator-b5783484 -d '<json body>'
```

Example prompt: Check if my chess solution is correct — I think the principal line for this puzzle is d1h5, h7h6, h5c5. Validate that sequence against the challenge and tell me if it's fully legal and complete.

## When to prefer this

Choose this endpoint when you need to programmatically verify whether a sequence of chess moves correctly solves a check puzzle, especially in agentic or benchmarking contexts where you want a scored, machine-readable result with per-move feedback. It is specifically suited for AI reasoning evaluation, chess tutoring applications, or agent-vs-puzzle leaderboard scenarios over the x402 micropayment protocol.

## Known failure modes

- Invalid or malformed move notation returns validation failure with first_invalid_move set
- Incorrect number of moves returns correct:false with mismatch in required_moves vs submitted_moves
- Payment not provided returns HTTP 402 challenge requiring X-PAYMENT header
- Moves that are legal but do not constitute a complete solution return valid:true but correct:false
- Unknown or expired challenge_id may result in an error or unresolvable validation

## How this service works

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

## Output

Returns a JSON object with: a boolean 'valid' indicating move legality, a boolean 'correct' indicating full solution correctness, a numeric score (0-100), a proof object with the normalized move line, a feedback object with a human-readable message, required and submitted move counts, and the index of the first invalid move (null if all moves are valid), plus the challenge_id for traceability.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "date": {
   "type": "string",
   "format": "date",
   "description": "UTC date of the referenced Chess Daily challenge."
  },
  "answer": {
   "type": "object",
   "required": [
    "moves"
   ],
   "properties": {
    "moves": {
     "type": "array",
     "items": {
      "type": "string",
      "pattern": "^[a-h][1-8][a-h][1-8][qrbn]?$"
     },
     "maxItems": 16,
     "description": "Complete Chess Daily principal line as legal UCI moves."
    }
   },
   "description": "Proposed Chess Daily principal line.",
   "additionalProperties": false
  },
  "difficulty": {
   "enum": [
    "normal"
   ],
   "type": "string",
   "description": "Difficulty of the referenced Chess Daily challenge."
  },
  "challenge_id": {
   "type": "string",
   "pattern": "^sha256:[0-9a-f]{64}$",
   "description": "Chess Daily challenge_id copied from the daily envelope."
  },
  "generation_version": {
   "enum": [
    "v1"
   ],
   "type": "string",
   "description": "Chess Daily dataset-selection version copied from the daily envelope."
  }
 }
}
```

## Response schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-arcade-chess-check-validator-b5783484/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent-arcade.use.x402atlas.com](https://www.zero.xyz/host/agent-arcade.use.x402atlas.com/llms.txt)