{"uid":"cap_aYPFibAkFvtNKtSVzm0Tr","slug":"chess-position-evaluator-stockfish-via-x402-51c4601d","name":"Chess Position Evaluator (Stockfish via x402)","description":"Evaluate a chess position with Stockfish: best move, centipawn/mate score, principal variation, and optional multipv. No mocks — a real single-threaded Stockfish 10 (asm.js) runs in-isolate per call.","url":"https://chess-eval.x402supply.com/tools/evaluate_position?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"fen":{"type":"string"},"depth":{"type":"integer","maximum":18,"minimum":1},"multipv":{"type":"integer","maximum":5,"minimum":1}}},"responseSchema":{"type":"json","example":{"pv":["d5","e5","d4","c3","Nc6","Nf3","dxc3"],"pvUci":["d7d5","e4e5","d5d4","c2c3","b8c6","g1f3","d4c3"],"engine":"stockfish 10 asm.js","evalCp":-29,"status":"ok","multipv":[{"pv":["d5","e5","d4","c3","Nc6","Nf3","dxc3"],"move":"d7d5","pvUci":["d7d5","e4e5","d5d4","c2c3","b8c6","g1f3","d4c3"],"evalCp":-29,"moveSan":"d5"}],"bestMove":"d7d5","timedOut":false,"fenEchoed":"rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1","bestMoveSan":"d5","perspective":"side-to-move","depthReached":10}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.01","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.01/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_Jlkr6meJwFh-ukHCFp5wx","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.01","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Evaluates a chess position using real Stockfish 10 (asm.js), returning the best move, centipawn/mate score, and principal variation for a given FEN string.","exampleAgentPrompt":"Can you evaluate this chess position — rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1 — at depth 14 and show me the best move along with the centipawn score?","exampleUseCases":[{"title":"Best move for critical game position","prompt":"I'm in a tough spot in my chess game — the FEN is r1bqk2r/ppp2ppp/2np1n2/2b1p3/2B1P3/2NP1N2/PPP2PPP/R1BQK2R w KQkq - 4 6. Can you run Stockfish at depth 16 and tell me the best move and the score?"},{"title":"Opening theory verification","prompt":"Can you check if e4 e5 Nf3 Nc6 Bb5 is the best line? Run a depth-12 Stockfish eval on rnbqkb1r/pppp1ppp/5n2/1B2p3/4P3/5N2/PPPP1PPP/RNBQK2R b KQkq - 3 3 and give me the top 3 candidate moves with their scores."},{"title":"Endgame accuracy check","prompt":"I want to know if I'm playing the endgame optimally — FEN is 8/8/4k3/8/4K3/8/4P3/8 w - - 0 1. Evaluate it with Stockfish at depth 18 and tell me the best move and whether there's a forced mate."}],"resultDescription":"Returns the best move in UCI notation, a centipawn score (or mate-in-N score), and the principal variation sequence. If multipv is set (1–5), returns multiple ranked candidate moves with individual scores and variations.","failureModes":["Invalid FEN string — position cannot be parsed, returns error","Depth out of range (must be 1–18) — returns validation error","multipv out of range (must be 1–5) — returns validation error","Timeout or isolate crash if position is extremely complex — may return partial results or error","Payment failure (x402) — call rejected before evaluation runs"],"whenToPreferThis":"Choose this endpoint when you need a real, deterministic Stockfish engine evaluation (not a mock or heuristic) for a single chess position given as FEN. It is ideal for agents that need authoritative centipawn scores, best-move recommendations, or principal variations without setting up a local engine. Supports up to 5 multipv lines and depth up to 18, making it suitable for both quick blunder checks and deeper positional analysis.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-30T00:31:43.590Z","isFirstParty":false,"canonicalSlug":"chess-position-evaluator-stockfish-via-x402-51c4601d"}