# 0200project / base-transaction-decoder

> A paid MCP server with one tool, `explain_transaction(tx_hash)`: deterministic plain-English decode of any Base mainnet transaction as strict JSON. No LLM in the response path.

## Documentation

- [Docs](https://0200project.com/docs/): tool contract, field reference, connection instructions
- [Playground](https://0200project.com/playground/): call the live server from the browser
- [FAQ](https://0200project.com/faq/): decoding Base transactions, MCP, x402 pay-per-call, risk flags, comparisons
- [Tools index](https://0200project.com/tools/): all tools published by 0200project

## API

- Simplest call, no headers beyond content-type, no account:
  POST https://api.0200project.com/explain
  Content-Type: application/json
  {"tx_hash": "0x..."}

- MCP endpoint: POST https://api.0200project.com/mcp (streamable HTTP, stateless)
  REQUIRED header, or the request is rejected before metering:
  Accept: application/json, text/event-stream

- OpenAPI: https://api.0200project.com/openapi.json
- MCP registry name: io.github.0200project/base-transaction-decoder

## Pricing

- 50 free calls per 24h per IPv4 address or IPv6 /64, shared by everyone behind it (an
  office, a VPN exit, a CI runner all draw from the same allowance). A window starts at the first call and ends 24 hours later; the next call starts a new one.
- Then $0.02 per call in USDC on Base via x402, or $9 for a 30-day pass covering
  10,000 calls. Rate limit 60 requests/minute. No account, no API key.
- Risk checks fail open: read `checks` before drawing conclusions from an empty
  `risk_flags`.