Foundry Zksync

An MCP (Model Context Protocol) server that exposes foundry-zksync CLI tools to AI assistants like Claude.

Tools

Tool	Description
init	forge init with automatic zkSync config
compile	forge build --zksync
test	forge test --zksync with filter/verbosity options
run_script	forge script --zksync with broadcast, sender, slow mode
deploy	forge create --zksync with structured output parsing
verify	forge verify-contract --zksync (Etherscan & zkSync Explorer)
install	forge install for dependency management
clean	forge clean to remove build artifacts
gas_report	forge test --gas-report for gas usage analysis
snapshot	forge snapshot for gas benchmarking
read_foundry_toml	Read and inspect project configuration
explain	Match errors/logs against a knowledge base of zkSync gotchas
cast_abi_encode	cast abi-encode
cast_abi_decode	cast abi-decode
cast_calldata_decode	cast calldata-decode
cast_call	cast call for read-only contract interaction
cast_send	cast send for state-changing transactions
cast_balance	cast balance for ETH balance queries
cast_nonce	cast nonce for transaction nonce queries
get_zksync_docs	Look up foundry-zksync documentation by topic
anvil_zksync	Start or check a local anvil-zksync dev node

Prerequisites

• Node.js >= 18
• foundry-zksync installed (foundryup-zksync)

Quick Start (npx)

No install needed — run directly with npx:

claude mcp add foundry-zksync -- npx -y foundry-zksync-mcp

Or add to claude_desktop_config.json / ~/.claude.json:

{
  "mcpServers": {
    "foundry-zksync": {
      "command": "npx",
      "args": ["-y", "foundry-zksync-mcp"]
    }
  }
}

Install from Source

git clone https://github.com/Jrigada/foundry-zksync-mcp.git
cd foundry-zksync-mcp
npm install
npm run build

Then register with Claude Code:

claude mcp add foundry-zksync node /absolute/path/to/foundry-zksync-mcp/dist/index.js

Key Management

All signing tools (deploy, cast_send, run_script) support multiple wallet methods. Choose based on your security needs:

Local Development (anvil-zksync)

For local dev with well-known test keys, use privateKey directly:

privateKey: "0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80"

These are the default anvil-zksync test accounts — they hold no real value.

Warning: Never use privateKey with keys that hold real funds. MCP tool parameters are visible to the AI assistant and may be logged.

Recommended for Production: Named Keystores

Keys are encrypted on disk — only the account name travels through MCP.

# Import a private key into a named keystore (interactive, key never shown)
cast wallet import deployer --interactive

# List your keystores
ls ~/.foundry/keystores/

Then use account: "deployer" in any signing tool. Forge will prompt for the password at runtime, or you can point to a password file with passwordFile.

Keystore Files

If you have an existing encrypted keystore JSON file (e.g. from Geth, MetaMask export):

keystore: "/path/to/keystore.json"
passwordFile: "/path/to/password.txt"

Hardware Wallets

ledger: true    # Ledger
trezor: true    # Trezor

Cloud KMS

aws: true       # AWS KMS (set AWS_KMS_KEY_ID env var)
gcp: true       # Google Cloud KMS (set GCP_PROJECT_ID, GCP_LOCATION, etc.)

Signing Method Summary

Method	Key Exposure	Best For
Hardware wallet	None (key never leaves device)	High-value production
Cloud KMS	None (key in HSM)	Automated production
Named keystore (account)	None through MCP (encrypted on disk)	General production use
Keystore file	None through MCP (encrypted on disk)	Existing workflows
privateKey	Visible to AI assistant	Local dev with test keys only

Project Structure

src/
  index.ts              MCP server entry point, registers all 21 tools
  knowledge.ts          Knowledge base (45+ entries) and system addresses
  tools/
    shared.ts           Profile field and env builder shared across forge tools
    init.ts             forge init with zkSync config
    compile.ts          forge build --zksync
    test.ts             forge test --zksync
    run_script.ts       forge script --zksync
    deploy.ts           forge create --zksync (structured output)
    verify.ts           forge verify-contract --zksync
    install.ts          forge install
    clean.ts            forge clean
    gas_report.ts       forge test --gas-report
    snapshot.ts         forge snapshot
    read_foundry_toml.ts  Read project config
    explain.ts          Error/log explanation with knowledge base
    get_zksync_docs.ts  Documentation lookup with embedded content
    cast_abi_encode.ts  cast abi-encode
    cast_abi_decode.ts  cast abi-decode
    cast_calldata_decode.ts  cast calldata-decode
    cast_call.ts        cast call
    cast_send.ts        cast send
    cast_balance.ts     cast balance
    cast_nonce.ts       cast nonce
    anvil_zksync.ts     anvil-zksync node management
  __tests__/            133 tests (vitest)