{"openapi":"3.1.0","servers":[{"url":"https://api.0200project.com","description":"Production"}],"externalDocs":{"url":"https://0200project.com/docs/","description":"Full documentation"},"info":{"title":"base-transaction-decoder","version":"0.1.4","contact":{"name":"0200project","url":"https://github.com/0200project/base-tx-explain/issues"},"license":{"name":"MIT","identifier":"MIT"},"description":"Plain-English, deterministic decode of any Base mainnet transaction. Strict JSON: summary, action type, assets moved, labeled counterparties, risk flags, gas in USD. No LLM in the response path.","x-guidance":"Two ways to call this. PLAIN HTTP: POST /explain with {\"tx_hash\":\"0x...\"} and read JSON back; it speaks x402, so an unpaid call returns a 402 challenge you pay and retry. MCP: this is also an MCP server (streamable HTTP). POST a JSON-RPC 2.0 envelope to /mcp with header \"Accept: application/json, text/event-stream\". Call method tools/call with name \"explain_transaction\" and arguments {\"tx_hash\": \"0x...\"} where tx_hash is a Base mainnet (chain id 8453) transaction hash. 50 free calls per IP per 24h, shared by everyone behind one address; afterwards the server returns an x402 payment challenge for $0.02 USDC on Base — attach the payment payload at _meta[\"x402/payment\"] per the x402 MCP transport and retry the same call. The result's structuredContent field carries the explanation object."},"paths":{"/explain":{"post":{"operationId":"explain","summary":"Explain a Base mainnet transaction in plain English","tags":["Blockchain"],"description":"Plain HTTP alternative to the MCP tool, for x402 clients that speak ordinary REST. 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Every check fails open: when an upstream source is unreachable no flag is emitted, which is indistinguishable in risk_flags from having looked and found nothing. An empty risk_flags is only meaningful when the relevant check is \"ok\" — alongside \"partial\", \"unavailable\" or \"inconclusive\" it means not checked, NOT clean. \"unavailable\" means the upstream sources were unreachable and a retry may get an answer; \"inconclusive\" means nothing failed but the check's method cannot answer for this input, so a retry will not help (today: first_interaction for a sender with more history than the lookup reads). 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