Programming Assignment: Ethereum Trading MCP Server

Overview

This project is a Model Context Protocol (MCP) server built in Rust that enables AI agents to query balances and execute token swaps on Ethereum.

Features

• get_balance: Query ETH and ERC20 token balances.
• get_token_price: Get current token price in USD using Chainlink price feeds.
• swap_tokens: Simulate a token swap on Uniswap V2.

Technical Stack

• Rust with Tokio for async runtime.
• ethers-rs for Ethereum RPC communication.
• rmcp for the MCP server framework.
• rust_decimal for financial precision.
• dotenv for managing environment variables.

Setup

1. Install Rust:

   curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
   

2. Clone the repository:

   git clone <repository-url>
   cd <repository-name>
   

3. Set up environment variables: Create a .env file in the root of the project and add your Ethereum RPC endpoint and a private key for simulations. You can use a service like Infura or Alchemy.

   # .env
   INFURA_PROJECT_ID=your_infura_project_id
   PRIVATE_KEY=your_wallet_private_key
   

4. Build the project:

   cargo build --release
   

5. Run the server:

   cargo run --release
   

   The server will start on 127.0.0.1:8080.

Example MCP Tool Call

Here is an example of calling the get_balance tool using curl.

Request:

curl -X POST -H "Content-Type: application/json" -d '{
  "jsonrpc": "2.0",
  "method": "get_balance",
  "params": {
    "wallet_address": "0xAb5801a7D398351b8bE11C439e05C5B3259aeC9B"
  },
  "id": 1
}' http://127.0.0.1:8080

Response:

{
  "jsonrpc": "2.0",
  "result": {
    "balance": "..."
  },
  "id": 1
}

Design Decisions

• ethers-rs vs. alloy: I chose ethers-rs as it is more mature and has extensive documentation, which is beneficial for a project with a tight deadline.
• Uniswap V2 for Swaps: I implemented swaps using Uniswap V2 for simplicity. The V2 router provides straightforward functions like swapExactTokensForTokens, which is easier to integrate than V3's more complex architecture.
• Environment Variables for Secrets: Sensitive information like the Infura project ID and private keys are managed through a .env file, which is a standard and secure practice.

Known Limitations

• Limited Token Support: The get_token_price and swap_tokens tools currently support a hardcoded list of tokens (ETH, DAI, USDC). This could be extended by using a dynamic token list or a discovery mechanism.
• Uniswap V2 Only: The swap functionality is limited to Uniswap V2. Adding V3 support would require a more complex implementation to handle concentrated liquidity and path finding.
• Basic Error Handling: The error handling is basic. A production-ready server would need more robust error handling and reporting.

Tests

To run the tests, use the following command:

cargo test

The tests cover the core functionality of the MCP tools. Note that the tests require a valid INFURA_PROJECT_ID and PRIVATE_KEY in the .env file to run.