Web3MCP
Web3MCP Protocol • Open Standard for EVM

Bring Your Protocol
Into The Agent Era.

An open standard for EVM protocols to publish verifiable tool manifests under their ENS name. Agents read contracts and simulate state diffs; users sign in their own wallet. Zero custom servers. Zero key custody.

See How It WorksRead Our Documentation
How It Works

Bring your protocol to AI agents in three easy steps

From ENS text-record publication to live simulation and human wallet approval.

01

Publish via ENS.

Write your tool manifest and ABI into ENS text records under your domain. An ENSv2 deployer updates tools with zero cloud infrastructure and zero custody risk.

agentswap.web3mcp.eth
● Owner-verified
org.web3mcp.manifest{ "tools": ["swapExactTokens"], "v": "0.1" }
Digest (keccak256)0x7a1c...94dE
✓ Validated
02

Discover & simulate.

AI hosts resolve protocols from ENS, query live on-chain state via gasless eth_call, and pre-flight state changes with eth_simulateV1 to prove exact balance deltas.

eth_simulateV1
● Ready to sign
ETH Balance-0.05 ETH
USDC Balance+110.42 USDC
Simulation ran with 0 errors
Oracle price within 3% tolerance
03

Approve in your wallet.

Transactions bridge to a local signing page. The user inspects decoded function calls and simulated token deltas, then signs directly in MetaMask or WalletConnect. Zero key custody.

Your Wallet0x9923...2ECb
Sends 0.05 ETH
AgentSwap+110.42 USDC
MetaMask • Sepolia
RejectSign
Integrations & Ecosystem

Seamless bridges for protocols, agents, and human signers.

Zero-overhead ENS discovery, instant MCP plugins for Claude Code & Codex, and air-gapped wallet execution.

Claude Code
Marketplace Live

Equip Claude with Real EVM Execution.

Install the official Web3MCP plugin in seconds. Claude resolves ENS manifests, executes gasless view calls, and triggers write simulations directly from your chat prompt.

terminal — claude
● plugin active
$ /plugin install web3mcp@evm-web3mcp
✓ Discovered Tool:agentswap.web3mcp.eth
exactInputSingle(tokenIn, tokenOut, amountIn)
Validation: Schema v0.1-evm OKSimulation Ready
Open Installation Guide
Protocol Publisher
ENSv2 Verified

Serverless Smart Contract Tools.

Publish tool manifests directly under your ENS domain text records. Zero cloud servers to maintain and zero custody risk.

Domain:agentswap.web3mcp.eth
Record:org.web3mcp.manifest
Digest:0x7a1c...94dE (keccak256)
Deployer Key: Non-root● Owner-Verified
Read Manifest Spec
Open Protocol
Universal Stdio / SSE

Standard MCP for Any Agent.

Connect @web3mcp/mcp to OpenAI Codex, Cursor, Zed, or custom LLM frameworks. Fully compliant with Anthropic Model Context Protocol specifications.

Transport:stdio (JSON-RPC 2.0)
Server:@web3mcp/mcp@0.0.1
Discovery:tools/list (dynamic)
Status: Active BridgeListening on stdin
Configure Codex Server
Zero Key Custody
Local Signing Host

Human-in-the-Loop Wallet Approval.

Every state-changing write halts for human inspection on a local signing page. View decoded parameters, simulated token inflows/outflows, and approve in MetaMask.

eth_simulateV1: 0 Reverts
Oracle Check: Within ±0.2%
Outflow:0.4210 → 0.3710 (-0.05 ETH)
Simulated Inflow:27.13 → 137.55 (+110.42 USDC)
Inspect approve-ui Architecture
Security Invariants

Security Invariants By Design.

Core protocol guarantees enforced mechanically at every execution step.

Zero Key Custody
Air-Gapped Wallet Boundary

Private keys never touch agent memory. All state-changing transactions bridge to your local browser for wallet approval.

Air-Gapped
State Diff Proofs
Atomic Pre-Flight Simulation

Every write call is simulated via eth_simulateV1 before prompting, proving exact token inflows, outflows, and gas.

eth_simulateV1
ENS Source of Truth
Decentralized Registry

Manifests reside on-chain under the protocol's ENS text records, verified cryptographically by keccak256 digests.

Owner-Verified
Fail-Closed Boundary
Zero-Trust Schema Validation

Malformed signatures, unverified targets, or ABI mismatches immediately halt execution before user interaction.

Fail-Closed
Zero-custody standard verified across all client adaptersRead Full Specification
Questions & Answers

Frequently Asked Questions.

Technical details on security, key custody, ENS integration, and architecture.

01What is Web3MCP?
Web3MCP is a draft open EVM standard for publishing smart-contract tool manifests under an ENS name. Its protocol design covers discovery, contract reads, write simulation, and user-approved signing through one generic MCP host.
02Do protocols have to host an MCP server?
No. Publishers put the manifest and digest in ENS text records; the generic host discovers, verifies, reads, simulates, and hands writes to the user wallet. A development-only manifest directory is also available for fixture testing.
03Can an AI agent sign transactions or move funds?
No. The model never receives or uses a private key. Writes are validated, simulated with eth_simulateV1, shown with decoded calls and asset changes, and handed to the user’s local signing page for wallet approval.
04Why is ENS the source of truth?
The protocol uses the publisher’s ENS name as the authoritative registry. org.web3mcp.manifest stores the exact JSON and org.web3mcp.digest stores its keccak256 digest. An index such as Arkiv may help agents find names, but a host must re-read and verify ENS before using a manifest.
05What does 'Owner-Verified' mean?
A contract is Owner-Verified when its ENS primary name points back to the publishing name. If that reverse relationship is absent, the contract is labeled Name-Only: the publishing ENS name remains the authority, but the host should request extra confirmation.
06What is implemented today?
The SDK discovers and verifies ENS manifests, checks contract code and trust, executes reads, prepares and simulates writes, and returns a local wallet signing handoff. The MCP server also reports write status. The current tested integration targets Ethereum Sepolia; configure a compatible chain client and RPC for other EVM deployments.