Ethereum DeFi Skill

Interact with the Ethereum blockchain for DeFi, token management, ENS resolution, smart contract calls, ERC-8004 agent identity, and Ethereum Attestation Service.

MCP Endpoint

For local development, use http://localhost:3004/mcp.

Tools

DeFi — Prices & Gas

#### eth_get_price Get token price from Chainlink data feed via on-chain AggregatorV3Interface.

Parameters:

• feed_address (string, optional, default ETH/USD) — Chainlink price feed contract address
• chain (string, optional, default "ethereum") — Chain name

Known feeds (Ethereum mainnet):

• ETH/USD: 0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419
• BTC/USD: 0xF4030086522a5bEEa4988F8cA5B36dbC97BeE88c
• LINK/USD: 0x2c1d072e956AFFC0D435Cb7AC38EF18d24d9127c
• USDC/USD: 0x8fFfFfd4AfB6115b954Bd326cbe7B4BA576818f6

Returns: Price, round ID, updated timestamp.

#### eth_get_gas_price Get current gas price in Gwei.

Returns: Gas price in Gwei and Wei.

#### eth_estimate_gas Estimate gas for a transaction.

Parameters:

• from (string, required) — Sender address
• to (string, required) — Recipient address
• data (string, optional) — Hex-encoded calldata
• value (string, optional) — Value in Wei (hex)

Returns: Estimated gas units.

#### eth_get_fee_history Get fee history for recent blocks (EIP-1559).

Parameters:

• block_count (string, optional, default "5") — Number of blocks
• newest_block (string, optional, default "latest") — Block tag
• reward_percentiles (string, optional) — Comma-separated percentiles

Returns: Base fees, gas used ratios, reward percentiles per block.

Accounts & Tokens

#### eth_get_balance Get ETH balance for an address.

Parameters:

• address (string, required) — Ethereum address (0x...)
• block (string, optional, default "latest") — Block number or tag

Returns: Balance in ETH and Wei.

#### eth_get_token_balance Get ERC-20 token balance.

Parameters:

• token_address (string, required) — ERC-20 contract address
• owner_address (string, required) — Owner address

Returns: Token balance (raw and formatted).

#### eth_get_transaction Get transaction details by hash.

Parameters:

• tx_hash (string, required) — Transaction hash (0x...)

Returns: Full transaction details.

#### eth_get_block Get block by number.

Parameters:

• block_number (string, optional, default "latest") — Block number (hex) or tag
• full_transactions (bool, optional, default false) — Include full tx objects

Returns: Block header and transactions.

#### eth_get_transaction_receipt Get transaction receipt with logs.

Parameters:

• tx_hash (string, required) — Transaction hash

Returns: Receipt with status, gas used, logs.

ENS (Ethereum Name Service)

#### eth_resolve_ens Resolve ENS name to Ethereum address.

Parameters:

• name (string, required) — ENS name (e.g. "vitalik.eth")

Returns: Resolved address.

#### eth_lookup_ens Reverse lookup: address to ENS name.

Parameters:

• address (string, required) — Ethereum address

Returns: Primary ENS name if set.

Smart Contracts

#### eth_call_contract Execute a read-only smart contract call.

Parameters:

• to (string, required) — Contract address
• data (string, required) — Hex-encoded calldata
• block (string, optional, default "latest") — Block number or tag

Returns: Hex-encoded return data.

#### eth_encode_function ABI-encode a function call (compute selector + encode args).

Parameters:

• function_sig (string, required) — Function signature (e.g. "transfer(address,uint256)")
• args (string, required) — JSON array of hex-encoded arguments

Returns: Complete hex calldata.

ERC-8004 Agent Registry

#### eth_register_agent_8004 Describe registration of an AI agent in the ERC-8004 on-chain registry.

Parameters:

• agent_name (string, required) — Agent display name
• capabilities (string, required) — Comma-separated capability list
• metadata_uri (string, optional) — URI to agent metadata JSON

Returns: Registration instructions and expected transaction data.

#### eth_lookup_agent_8004 Look up an agent in the ERC-8004 registry.

Parameters:

• agent_id (string, required) — Agent ID or address

Returns: Agent info, capabilities, reputation score.

EAS (Ethereum Attestation Service)

#### eth_get_attestation Query an attestation from EAS by UID.

Parameters:

• uid (string, required) — Attestation UID

Returns: Attestation schema, attester, recipient, data, timestamp.

Common Workflows

Check Token Price & Balance

1. eth_get_price(feed_address="0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419") — ETH/USD price
2. eth_get_balance(address="0x...") — ETH balance
3. eth_get_token_balance(token_address="0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48", owner_address="0x...") — USDC balance

Deploy & Call Contract

1. eth_encode_function(function_sig="transfer(address,uint256)", args='["0xrecipient","0x amount"]') — Build calldata
2. eth_estimate_gas(from="0x...", to="0xcontract", data="0x...") — Estimate gas
3. eth_get_gas_price() — Check current gas

Verify Agent Identity

1. eth_lookup_agent_8004(agent_id="0x...") — Check agent registration
2. eth_get_attestation(uid="0x...") — Verify EAS attestation