Ethereum Transaction Builder

Transaction MCP Server

An MCP (Model Context Protocol) server providing comprehensive Ethereum transaction capabilities including building, signing, decoding, and analysis for both legacy and EIP-1559 transactions.

Features

Tools (15 total)

Transaction Building & Signing

• build_transaction - Build an unsigned transaction
• sign_transaction - Sign a transaction with a private key
• build_and_sign_transaction - Build and sign in one step

Transaction Decoding

• decode_raw_transaction - Decode a signed raw transaction
• decode_unsigned_transaction - Decode an unsigned transaction
• recover_transaction_signer - Recover signer from signed transaction

Transaction Analysis

• estimate_transaction_cost - Estimate gas cost in ETH
• validate_transaction - Validate transaction fields
• compare_transactions - Compare two transactions

Gas Utilities

• convert_gas_units - Convert between wei, gwei, ether
• calculate_max_cost - Calculate maximum transaction cost

Data Encoding

• encode_transfer - Encode ERC-20 transfer calldata
• encode_function_call - Encode arbitrary function call
• decode_calldata - Decode transaction input data

Serialization

• serialize_transaction - RLP encode a transaction

Resources (4 total)

• transaction-types - Documentation on transaction types (Legacy, EIP-2930, EIP-1559)
• gas-estimation - Guide to gas estimation and optimization
• chain-ids - Chain ID reference for all networks
• eip-1559 - EIP-1559 fee mechanism explained

Prompts (4 total)

• build_transfer_workflow - Guide through building an ETH transfer
• token_transfer_workflow - Guide through ERC-20 token transfers
• decode_transaction_workflow - Help decode and analyze transactions
• gas_optimization_workflow - Optimize transaction gas costs

Installation

pip install transaction-mcp-server

Or install from source:

cd transaction-mcp-server
pip install -e .

Usage

Run the server

transaction-mcp-server

Configure in Claude Desktop

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

Tool Examples

Sign a Simple Transfer

# Input
{
    "to": "0x742d35Cc6634C0532925a3b844Bc9e7595f5b4E2",
    "value": "1000000000000000000",  # 1 ETH in wei
    "nonce": 0,
    "chain_id": 1,
    "max_fee_per_gas": "30000000000",
    "max_priority_fee_per_gas": "2000000000",
    "private_key": "0x..."
}

# Output
{
    "raw_transaction": "0x02f8...",
    "transaction_hash": "0x...",
    "from": "0xABC...",
    "to": "0x742...",
    "value_eth": "1.0",
    "type": "EIP-1559"
}

Decode a Transaction

# Input
{
    "raw_transaction": "0x02f8..."
}

# Output
{
    "type": "EIP-1559 (Type 2)",
    "chain_id": 1,
    "nonce": 0,
    "to": "0x742...",
    "value_wei": "1000000000000000000",
    "value_eth": "1.0",
    "max_fee_per_gas_gwei": "30.0",
    "max_priority_fee_per_gas_gwei": "2.0"
}

Transaction Types

Type	EIP	Description
Legacy (0)	-	Original Ethereum transactions
Access List (1)	EIP-2930	With access list for gas savings
Dynamic Fee (2)	EIP-1559	Base fee + priority fee model

Security Notes

1. Private keys are NEVER logged or persisted
2. Transactions are signed OFFLINE - no network connection
3. Raw transactions must be broadcast separately
4. For educational and development purposes only

Chain IDs

Chain	ID
Ethereum Mainnet	1
Goerli	5
Sepolia	11155111
Polygon	137
Arbitrum One	42161
Optimism	10
Base	8453

License

MIT