onesource-api-mcp

MCP server for OneSource blockchain data. 22 named tools for balances, NFTs, transactions, events, and live chain queries via x402 micropayments.

npx onesource-api-mcp

Install

# Claude Code
claude mcp add onesource-api -- npx onesource-api-mcp

# Claude Desktop / Cursor — add to MCP config:
{
  "mcpServers": {
    "onesource-api": {
      "command": "npx",
      "args": ["-y", "onesource-api-mcp"]
    }
  }
}

Tools (22)

Live Chain Data (12 tools)

| Tool | Description | |------|-------------| | 1s_allowance_live | ERC20 allowance check | | 1s_contract_info_live | Contract type detection via ERC165 | | 1s_erc1155_balance_live | ERC1155 balance via RPC | | 1s_erc20_balance_live | ERC20 balance via balanceOf | | 1s_erc20_transfers_live | ERC20 Transfer logs via eth_getLogs | | 1s_erc721_tokens_live | ERC721 token enumeration | | 1s_events_live | Event logs via eth_getLogs | | 1s_multi_balance_live | ETH + multiple ERC20 balances | | 1s_nft_metadata_live | NFT metadata via tokenURI | | 1s_nft_owner_live | NFT owner via ownerOf | | 1s_total_supply_live | Token total supply | | 1s_tx_details_live | Transaction + receipt via RPC |

Chain Utilities (10 tools)

| Tool | Description | |------|-------------| | 1s_contract_code | Contract bytecode | | 1s_ens_resolve | ENS name/address resolution | | 1s_estimate_gas | Gas estimation | | 1s_network_info | Chain ID, block number, gas price | | 1s_nonce | Transaction count | | 1s_pending_block | Pending block from mempool | | 1s_proxy_detect | Proxy contract detection | | 1s_simulate_call | Simulate eth_call | | 1s_storage_read | Read storage slot | | 1s_tx_receipt | Transaction receipt |

Networks

All tools accept an optional network parameter:

| Network | Description | |---------|-------------| | ethereum | Ethereum mainnet (default) | | sepolia | Ethereum Sepolia testnet | | avax | Avalanche C-Chain |

Payment (x402)

Endpoints are priced in USDC on Base via x402. When the backend has payments enabled, tool calls return a 402 with payment details.

Automatic payments: Set X402_PRIVATE_KEY to a funded EVM wallet key. The server will automatically sign and settle USDC payments for each tool call.

X402_PRIVATE_KEY=0x... npx onesource-api-mcp

Without this key, 402 responses are returned as tool errors with a descriptive message.

Configuration

| Variable | Default | Description | |----------|---------|-------------| | ONESOURCE_BASE_URL | https://skills.onesource.io | Skills API endpoint | | X402_PRIVATE_KEY | — | EVM private key (0x-prefixed hex) for automatic x402 USDC payments on Base |

License

MIT