# Ethereum & EVM Message Signing

Signs EIP-191 messages and EIP-712 typed data, checks signatures and recovers the signer. Useful when your agent has to handle Ethereum signatures.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 28
- Author: nirholas
- License: not stated · policy=link-only · description only; the file stays with the author
- Source: https://github.com/nirholas/ethereum-wallet-toolkit/tree/HEAD/signing-mcp-server
- Updated: 2026-10-19
- HTML: https://affpapa.org/en/nevibecode/mcp/ethereum-evm-message-signing

## What it does

Twelve tools come with the server. The EIP-191 set covers signing plain text and hex bytes, verifying a signature, and getting the signer address back out of it. The EIP-712 set signs structured data, verifies it, recovers the signer, and hashes typed data on its own. Signature helpers split a signature into `v`, `r`, `s`, put it back together, and convert `v` between 27/28 and 0/1. One more tool, `sign_hash`, signs a raw 32-byte hash and only runs once you acknowledge the risk.

Four resources ship with it: the EIP-191 and EIP-712 specs, notes on Ethereum signature formats, and templates for common typed structures such as ERC-20 Permit, Permit2, DEX orders, vote delegation and the Mail example. Four prompts walk through message signing, typed data, debugging a verification, and ERC-20 permits.

Keys are never logged or stored. All cryptography relies on `eth-account`. The author labels the project as a learning and development tool, so real wallet keys belong elsewhere.

## Requirements
- Needs: Python and uv (commands run via uvx)

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add signing-mcp-server -- uvx signing-mcp-server
```
uvx runs the command named after the package; if the README names another one, use uvx --from signing-mcp-server <command>

### Codex

**Platform CLI**
```bash
codex mcp add signing-mcp-server -- uvx signing-mcp-server
```
uvx runs the command named after the package; if the README names another one, use uvx --from signing-mcp-server <command>

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "signing-mcp-server": {
            "command": "uvx",
            "args": [
                "signing-mcp-server"
            ]
        }
    }
}
```
uvx runs the command named after the package; if the README names another one, use uvx --from signing-mcp-server <command>

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "signing-mcp-server": {
            "type": "stdio",
            "command": "uvx",
            "args": [
                "signing-mcp-server"
            ]
        }
    }
}
```
uvx runs the command named after the package; if the README names another one, use uvx --from signing-mcp-server <command>

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add signing-mcp-server uvx signing-mcp-server
```
uvx runs the command named after the package; if the README names another one, use uvx --from signing-mcp-server <command>

## When to use it
- sign a text message in EIP-191 personal_sign format
- verify a signature and find out which address produced it
- split a signature into v, r, s and rebuild it
- compute an EIP-712 hash for a Permit structure without signing
- convert v from 27/28 to 0/1

## Example prompts
- Sign the message “Hello, Ethereum!” with the key in my env var and show me v, r and s
- Check whether signature `0x...` for the Hello message matches address `0xABC123...`
- Decompose `0x...` into v, r, s and normalize v to the 0/1 form

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From the same set: [nirholas/ethereum-wallet-toolkit](https://affpapa.org/en/nevibecode/by/nirholas/ethereum-wallet-toolkit.md) — 5 cards

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