Signing MCP Server

An MCP (Model Context Protocol) server providing comprehensive Ethereum message signing capabilities including EIP-191 personal_sign and EIP-712 typed structured data.

Features

Tools (12 total)

EIP-191 Message Signing

• sign_message - Sign a text message using EIP-191 personal_sign format
• sign_message_hex - Sign hex-encoded bytes using EIP-191 format
• verify_message - Verify an EIP-191 signed message
• recover_signer - Recover signer address from a signed message

EIP-712 Typed Data

• sign_typed_data - Sign EIP-712 typed structured data
• verify_typed_data - Verify an EIP-712 typed data signature
• recover_typed_data_signer - Recover signer from typed data signature
• hash_typed_data - Compute EIP-712 hash without signing

Signature Utilities

• decompose_signature - Break down signature into v, r, s components
• compose_signature - Compose signature from v, r, s components
• normalize_signature - Convert between signature formats (27/28 vs 0/1 for v)

Advanced Operations

• sign_hash - Sign a raw 32-byte hash (requires acknowledgement)

Resources (4 total)

• eip191-specification - Complete EIP-191 signed data standard
• eip712-specification - Complete EIP-712 typed data standard
• signature-formats - Documentation on Ethereum signature formats
• common-typed-data - Templates for common EIP-712 structures

Prompts (4 total)

• sign_message_workflow - Guide through message signing process
• typed_data_workflow - Guide through EIP-712 typed data signing
• signature_verification - Help verify and debug signatures
• permit_signing - Specialized workflow for ERC-20 permits

Installation

pip install signing-mcp-server

Or install from source:

cd signing-mcp-server
pip install -e .

Usage

Run the server

signing-mcp-server

Configure in Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "signing": {
      "command": "signing-mcp-server"
    }
  }
}

Tool Examples

Sign a Message (EIP-191)

# Input
{
    "message": "Hello, Ethereum!",
    "private_key": "0x..."
}

# Output
{
    "message": "Hello, Ethereum!",
    "signer": "0xABC123...",
    "signature": "0x...",
    "v": 28,
    "r": "0x...",
    "s": "0x...",
    "message_hash": "0x..."
}

Sign Typed Data (EIP-712)

# Input
{
    "typed_data": {
        "types": {...},
        "primaryType": "Permit",
        "domain": {...},
        "message": {...}
    },
    "private_key": "0x..."
}

# Output
{
    "signer": "0xABC123...",
    "signature": "0x...",
    "domain_separator": "0x...",
    "struct_hash": "0x...",
    "signing_hash": "0x..."
}

Verify a Signature

# Input
{
    "message": "Hello, Ethereum!",
    "signature": "0x...",
    "expected_address": "0xABC123..."
}

# Output
{
    "is_valid": true,
    "recovered_address": "0xABC123...",
    "expected_address": "0xABC123...",
    "match": true
}

Security Notes

1. Private keys are NEVER logged or persisted
2. sign_hash requires explicit risk acknowledgement - signing raw hashes can be dangerous
3. All operations use eth-account's secure implementations
4. For educational and development purposes only

EIP-712 Templates

The server includes templates for common typed data structures:

• Permit - ERC-20 token permits (EIP-2612)
• Permit2 - Uniswap's universal permit system
• Order - DEX limit orders
• Delegation - Voting power delegation
• Mail - EIP-712 specification example

License

MIT