Web3 MCP Server

What is Web3 MCP Server?

Web3 MCP Server is a Model Context Protocol (MCP) server that interacts with Ethereum networks using the viem library. It supports querying balances, transactions, blocks, ENS names, and more, and is intended for developers building AI‑powered tools that need on‑chain data.

How to use Web3 MCP Server?

Install dependencies with npm install, optionally create a .env file to set CHAIN_ENV (defaults to mainnet), and start the server with npm start. You can switch networks at runtime by setting the CHAIN_ENV environment variable to mainnet, goerli, sepolia, or local. Use the mcp‑cli tool (npx @wong2/mcp-cli npm start) for interactive testing. For integration with Claude or Cursor IDE, build the server with npm run build and add a JSON MCP configuration pointing to the built index.js file.

Key features of Web3 MCP Server

• Get ETH and ERC-20 token balances
• Query transaction and block details
• ENS name resolution and reverse lookup
• Call read‑only contract methods
• Supports mainnet, Goerli, Sepolia, and local (Hardhat) networks

Use cases of Web3 MCP Server

• Fetching wallet balances across multiple Ethereum networks
• Inspecting transaction receipts and block data
• Resolving ENS names to addresses and vice versa
• Reading on‑chain state via contract method calls
• Building AI agents that require real‑time Ethereum data

FAQ from Web3 MCP Server

Which networks does Web3 MCP Server support?

Mainnet, Goerli, Sepolia, and a local Hardhat network. The network is selected via the CHAIN_ENV environment variable.

How do I change the network?

Set the CHAIN_ENV environment variable to one of mainnet, goerli, sepolia, or local before starting the server. If not set, the server defaults to mainnet.

Does Web3 MCP Server support sending transactions?

Yes, write (transaction) support has been added for testnet and local networks, as indicated in the project’s completed next‑steps list.

How can I test the server without a full integration?

Use the mcp‑cli tool by running npx @wong2/mcp-cli npm start from the server directory. This allows you to list tools, call them, and inspect capabilities interactively.

What are the runtime requirements for Web3 MCP Server?

Node.js and npm are required. Dependencies are installed via npm install. For local networks, a Hardhat node must be running at http://127.0.0.1:8545.