rsynth-mcp

the execution-proof MCP for Base. query and verify on-chain ExecutionLog anchors from any MCP client. public, independent verifiability - anyone can check anchored proofs via the contract, not just this server.

tools

verify_execution · paid · $0.01 USDC via x402
- verify an ExecutionLog anchor by tx hash. recovers EIP-191 signer.
- returns payload hash, block, timestamp.
- optional payload arg for local hash-match check.
query_signers · free
- list addresses that have anchored ExecutionLog records, with anchor counts and first-seen block.

install

with claude code:

claude mcp add rsynth https://<vercel-host>/api/mcp

primitive

ExecutionLog on base mainnet · contract · 0xd5A9DAF8F2134b61b73cEfaF5c9094EA162f1a1c · basescan · https://basescan.org/address/0xd5A9DAF8F2134b61b73cEfaF5c9094EA162f1a1c · event · ExecutionRecorded(signer, payloadHash, timestamp)

why on-chain

cryptographic (EIP-191) + base mainnet finality. alternatives anchor where only their server can read (off-chain stat boards, in-memory hash chains, TEE attestations). this one anchors where anyone can read - the same verification works from a contract call, not just this server.

stack

next.js 15 app router · vercel deploy
x402-mcp v0.1 · paid MCP tool primitive
viem · base mainnet rpc + EIP-191 recovery
verify code vendored from r402 (see src/r402/README.md for sync procedure)

config

copy .env.example to .env.local and fill:

BASE_RPC_URL · base mainnet rpc
PAYMENT_RECIPIENT_ADDRESS · x402 USDC payee
X402_FACILITATOR_URL · optional, defaults to openx402

dev

pnpm install
pnpm typecheck
pnpm test
pnpm dev

dev server at http://localhost:3000 · MCP endpoint at /api/mcp.

roadmap

v0.1 · verify_execution + query_signers
v0.2 · anchor_execution (write tx via self-hosted relayer)
v0.2 · ERC-8004 signer -> agent_id resolution
v0.2 · upstash KV cache on query_signers (when load demands)

MCP Servers