EVM Blockchain Skill

Query EVM-compatible blockchain data across 8 chains with USD pricing. 14 commands: wallet portfolio, token info, transactions, activity, gas tracker, network stats, price lookup, multi-chain scan, whale detection, ENS resolution, allowance checker, contract inspector, and transaction decoder.

Supports 8 chains: Ethereum, BNB Chain (BSC), Base, Arbitrum One, Polygon, Optimism, Avalanche (C-Chain), zkSync Era.

No API key needed. Zero external dependencies — Python standard library only (urllib, json, argparse, threading).

Supersedes the standalone base skill. Base-specific tokens (AERO, DEGEN, TOSHI, BRETT, WELL, cbETH, cbBTC, wstETH, rETH) and all Base RPC functionality previously living under optional-skills/blockchain/base/ have been folded into this skill. Pass --chain base to any command for Base coverage.

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When to Use

• User asks for a wallet balance or portfolio on any EVM chain
• User wants to check the same wallet across ALL chains at once
• User wants to inspect a transaction by hash (or decode what it did)
• User wants ERC-20 token metadata, price, supply, or market cap
• User wants recent transaction history for an address
• User wants current gas prices or to compare fees across chains
• User wants to find large whale transfers in recent blocks
• User asks to resolve an ENS name (vitalik.eth) or reverse-lookup an address
• User wants to check if a contract has dangerous token approvals
• User wants to inspect a smart contract (proxy? ERC-20? ERC-721? bytecode size?)
• User wants to compare gas costs across chains before a transaction

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Prerequisites

Python 3.8+ standard library only. No pip installs required. Pricing: CoinGecko free API (rate-limited, ~10-30 req/min). ENS: ensideas.com public API. Tx decoding: 4byte.directory public API.

Override RPC endpoint: export EVM_RPC_URL=https://your-rpc.com

Helper script path: ~/.hermes/skills/blockchain/evm/scripts/evm_client.py

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Quick Reference

SCRIPT=~/.hermes/skills/blockchain/evm/scripts/evm_client.py

# Network & prices
python3 $SCRIPT stats                            # Ethereum stats
python3 $SCRIPT stats --chain arbitrum           # Arbitrum stats
python3 $SCRIPT compare                          # Gas + prices ALL 8 chains

# Wallet
python3 $SCRIPT wallet 0xd8dA...96045            # Portfolio (ETH + ERC-20)
python3 $SCRIPT wallet 0xd8dA...96045 --chain bsc
python3 $SCRIPT multichain 0xd8dA...96045        # Same wallet on ALL chains

# Tokens & prices
python3 $SCRIPT price ETH
python3 $SCRIPT price 0xdAC1...1ec7              # By contract address
python3 $SCRIPT token 0xdAC1...1ec7              # ERC-20 metadata + market cap

# Transactions
python3 $SCRIPT tx 0x5c50...f060                 # Transaction details
python3 $SCRIPT decode 0x5c50...f060             # Decode input data (4byte.directory)
python3 $SCRIPT activity 0xd8dA...96045          # Recent transactions

# Gas
python3 $SCRIPT gas                              # Gas prices + cost estimates
python3 $SCRIPT gas --chain optimism

# Security
python3 $SCRIPT allowance 0xd8dA...96045         # Dangerous ERC-20 approvals
python3 $SCRIPT contract 0xdAC1...1ec7           # Contract inspection (proxy? standards?)

# ENS
python3 $SCRIPT ens vitalik.eth                  # Name -> address + profile
python3 $SCRIPT ens 0xd8dA...96045               # Address -> ENS name

# Whale detection
python3 $SCRIPT whale                            # Large transfers (last 20 blocks, >$10k)
python3 $SCRIPT whale --blocks 50 --min-usd 100000 --chain arbitrum

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Procedure

0. Setup Check

python3 --version   # 3.8+ required
python3 ~/.hermes/skills/blockchain/evm/scripts/evm_client.py stats

1. Wallet Portfolio

Native balance + known ERC-20 tokens, sorted by USD value.

python3 $SCRIPT wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
python3 $SCRIPT wallet 0xd8dA... --chain bsc --no-prices   # faster

2. Multi-Chain Scan

Scans all 8 chains simultaneously for the same address using threads.

python3 $SCRIPT multichain 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045

Output: per-chain native balance + token holdings + grand total USD.

3. Compare (Gas + Prices)

All 8 chains queried in parallel. Shows cheapest/most expensive chain.

python3 $SCRIPT compare

4. Transaction Details & Decode

python3 $SCRIPT tx 0x5c504ed432cb51138bcf09aa5e8a410dd4a1e204ef84bfed1be16dfba1b22060
python3 $SCRIPT decode 0x5c504ed...   # Shows human-readable function signature

Decode uses 4byte.directory to translate 0xa9059cbb -> transfer(address,uint256).

5. ENS Resolution

python3 $SCRIPT ens vitalik.eth          # -> 0xd8dA... + avatar + social links
python3 $SCRIPT ens 0xd8dA...96045       # -> vitalik.eth

6. Allowance Checker (Security)

Checks ERC-20 approvals granted to known DEX/bridge contracts.

python3 $SCRIPT allowance 0xYourWallet

Flags UNLIMITED approvals as HIGH risk.

7. Contract Inspector

python3 $SCRIPT contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48   # USDC (proxy)
python3 $SCRIPT contract 0xdAC17F958D2ee523a2206206994597C13D831ec7   # USDT (ERC-20)

Detects: proxy (EIP-1967/EIP-1167), ERC-20, ERC-721, ERC-165. Shows bytecode size and implementation address for proxies.

8. Whale Detection

python3 $SCRIPT whale                                    # ETH, last 20 blocks, >$10k
python3 $SCRIPT whale --blocks 50 --min-usd 50000 --chain bsc

9. Gas Tracker

python3 $SCRIPT gas
python3 $SCRIPT gas --chain polygon

Shows gwei price + USD cost for: transfer, ERC-20 transfer, approve, swap, NFT mint, NFT transfer.

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Supported Chains

Key	Name	Native	Chain ID
ethereum	Ethereum	ETH	1
bsc	BNB Chain	BNB	56
base	Base	ETH	8453
arbitrum	Arbitrum One	ETH	42161
polygon	Polygon	POL	137
optimism	Optimism	ETH	10
avalanche	Avalanche C	AVAX	43114
zksync	zkSync Era	ETH	324

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Pitfalls

• CoinGecko free tier: ~10-30 req/min. Use --no-prices for faster wallet scans.
• Public RPCs may throttle. Set EVM_RPC_URL to a private endpoint for production.
• wallet and allowance only check known token list (~30 tokens per chain). Use a block explorer for complete token discovery.
• activity scans recent blocks only (max 200). For full history, use Etherscan API.
• multichain runs 8 parallel threads — can trigger rate limits on public RPCs.
• ENS resolution depends on a single public endpoint (ensideas.com / ens.vitalik.ca) with no fallback. If that endpoint is down, ens will fail — re-run later or use a block explorer.
• Tx decoding depends on a single public endpoint (4byte.directory) with no fallback. Selectors not in their database show up as unknown.
• L2 gas estimates are L2-execution only. On rollups like Base, Arbitrum, Optimism, and zkSync, the actual transaction cost also includes an L1 data-posting fee that depends on calldata size and current L1 gas prices. The gas command does not estimate that L1 component. For Base specifically, see the network's L1 fee oracle (contract 0x420000000000000000000000000000000000000F).
• Address / tx-hash inputs are validated for 0x-prefix + correct length + hex, but EIP-55 checksum casing is not enforced (RPC endpoints accept any-case hex).

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Verification

# Should print current block, gas price, ETH price
python3 ~/.hermes/skills/blockchain/evm/scripts/evm_client.py stats

# Should resolve vitalik.eth to 0xd8dA...
python3 ~/.hermes/skills/blockchain/evm/scripts/evm_client.py ens vitalik.eth