Agent Protocol Overview

CheckAI defines a JSON-based protocol for AI agents to play chess. This protocol is the contract between the server and any AI agent connecting to it.

Rule Basis: FIDE Laws of Chess, effective January 1, 2023, adopted at the 93rd FIDE Congress in Chennai, India.

Role of the Agent

You are a chess-playing agent. Before each move, you receive the complete game state as a JSON object. You must return exactly one legal move as a JSON object.

• Illegal moves are never acceptable
• Output must be raw JSON — no text, no Markdown, no explanations
• Analyze the position, calculate all legal moves, and choose one

Communication Flow

Server                              Agent
  │                                   │
  │  ── Game State (JSON) ──────────► │
  │                                   │  Analyze position
  │                                   │  Calculate legal moves
  │  ◄── Move Output (JSON) ──────── │
  │                                   │
  │  Validate move                    │
  │  Update board                     │
  │  Check game-end conditions        │
  │                                   │
  │  ── Updated State (JSON) ───────► │
  │                                   │

Protocol Summary

Direction	Format	Content
Server → Agent	JSON	Complete game state
Agent → Server	JSON	One legal move or special action

The Chessboard

• 8×8 grid with 64 squares
• Files (columns): a to h
• Ranks (rows): 1 to 8 (1 = White home, 8 = Black home)
• Squares: two-character strings like "e4", "a1", "h8"

Piece Symbols

Following the FEN convention (uppercase = White, lowercase = Black):

Symbol	Piece	Color
K	King	White
Q	Queen	White
R	Rook	White
B	Bishop	White
N	Knight	White
P	Pawn	White
k	King	Black
q	Queen	Black
r	Rook	Black
b	Bishop	Black
n	Knight	Black
p	Pawn	Black

Next Steps

• Game State (Input) — JSON schema the agent receives
• Move Output — JSON schema the agent returns
• Chess Rules — Complete FIDE 2023 rule reference
• Special Actions — Draw claims, resignation
• Examples — Full worked examples