@one-source/mcp

Unified MCP server for OneSource — 27 tools for blockchain data and live chain queries in a single server.

What is MCP? The Model Context Protocol lets AI assistants call tools and access data sources. This server exposes both the OneSource blockchain API and its documentation as tools.

Quick Start

Claude Code

claude mcp add onesource -- npx -y @one-source/mcp@latest

Claude Desktop / Cursor

Add to your MCP config:

{
  "mcpServers": {
    "onesource": {
      "command": "npx",
      "args": ["-y", "@one-source/mcp@latest"]
    }
  }
}

Any MCP Client (stdio)

npx -y @one-source/mcp@latest

HTTP Server (self-hosted)

npx -y @one-source/mcp@latest --http
npx -y @one-source/mcp@latest --http --port=8080

Then connect your MCP client to http://localhost:3000/.

Health check: GET http://localhost:3000/health

Tools (27)

Blockchain API — Live Chain (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 |

Blockchain API — Chain Utilities (13 tools)

RPC only.

| Tool | Description | |------|-------------| | 1s_block_by_number | Block details by number via RPC | | 1s_block_number | Latest block number | | 1s_chain_id | EIP-155 chain ID | | 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 |

Setup & Ops (2 tools)

No authentication required.

| Tool | Purpose | When to use | |------|---------|-------------| | 1s_setup_check | Server health, version, auth status, setup instructions | First thing to call — checks if everything is configured | | 1s_report_bug | Report bugs to Slack (or GitHub Issues fallback) | When a tool errors or user wants to report an issue |

Networks

All blockchain API tools accept an optional network parameter:

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

Authentication

Blockchain API tools require authentication. Two options are available — if both are set, API key takes priority.

| Method | Variable | Description | |--------|----------|-------------| | API key | ONESOURCE_API_KEY | Unlimited calls, no per-call cost | | x402 micropayments | X402_PRIVATE_KEY | Pay-per-call via USDC on Base, no account required |

Option 1: API Key

1. Go to app.onesource.io and create an account.
2. Subscribe to a developer plan (Stripe checkout).
3. Navigate to API Keys and generate a key.
4. Copy the key — it starts with sk_.

Claude Code

claude mcp add onesource -e ONESOURCE_API_KEY=<key> -- npx -y @one-source/mcp@latest

Claude Desktop / Cursor

{
  "mcpServers": {
    "onesource": {
      "command": "npx",
      "args": ["-y", "@one-source/mcp@latest"],
      "env": {
        "ONESOURCE_API_KEY": "<key>"
      }
    }
  }
}

Any MCP Client (stdio)

ONESOURCE_API_KEY=<key> npx -y @one-source/mcp@latest

After adding, reload the MCP server and call 1s_setup_check — it should show Status: Configured (API key).

Option 2: x402 Micropayments

Pay-per-call via USDC on Base using x402. No account required — just an EVM wallet funded with USDC. The server handles payments transparently.

1. Get an EVM private key — export from MetaMask, Coinbase Wallet, or generate a fresh one. The key is a 64-character hex string. The 0x prefix is optional — both formats are accepted.
2. Pass the key to the server:

Claude Code

claude mcp add onesource -e X402_PRIVATE_KEY=<key> -- npx -y @one-source/mcp@latest

Claude Desktop / Cursor

{
  "mcpServers": {
    "onesource": {
      "command": "npx",
      "args": ["-y", "@one-source/mcp@latest"],
      "env": {
        "X402_PRIVATE_KEY": "<key>"
      }
    }
  }
}

Any MCP Client (stdio)

X402_PRIVATE_KEY=<key> npx -y @one-source/mcp@latest

3. Reload and find your wallet address — reload the MCP server, then call 1s_setup_check. It will show the wallet address derived from your key under "Wallet address".
4. Fund that address with USDC on Base — send USDC to the address shown, on the Base network. A few dollars ($1–5 USDC) is enough for hundreds of calls. Bridge from Ethereum mainnet if needed using the Base Bridge.
5. Verify — call 1s_network_info for ethereum. If it returns chain data, payments are working.

Security

Never commit keys to source control. Use environment variables, a .env file (excluded from git), or a secrets manager.

After any config change: Run /reload-plugins in Claude Code, or restart Claude Desktop / Cursor. The MCP server must be reloaded to pick up new environment variables.

Environment Variables

| Variable | Default | Description | |----------|---------|-------------| | ONESOURCE_API_KEY | — | OneSource API key for Bearer token auth. Takes priority over x402. | | X402_PRIVATE_KEY | — | EVM private key (64-char hex, 0x prefix optional) for automatic x402 USDC payments on Base |

Troubleshooting

1s_setup_check shows "Not configured" — Set either ONESOURCE_API_KEY or X402_PRIVATE_KEY. Reload the MCP server after setting either variable. If the key still isn't reaching the server, set it as a shell environment variable directly.

Getting 403 / wrong key active despite correct setup — A key set in your shell profile (e.g. ~/.zshrc, ~/.bash_profile) is picked up by the MCP server process even if it isn't in your Claude MCP config. Run echo $ONESOURCE_API_KEY in your terminal to check. If it prints a value you didn't intend, unset it (unset ONESOURCE_API_KEY) or explicitly clear it when adding the server: claude mcp add onesource -e ONESOURCE_API_KEY= -e X402_PRIVATE_KEY=<key> -- npx -y @one-source/mcp@latest. 1s_setup_check shows the first 6 characters of whichever key is active so you can confirm which one the server is using.

Instructions show wrong auth method after reinstall — /reload-plugins in Claude Code reconnects tools but may not refresh the system prompt the LLM sees. If you switch auth method (e.g. API key → x402), do a full Claude Code restart to ensure the instructions reflect the new auth.

"MCP server onesource already exists" error — Run claude mcp remove onesource first, then re-add.

Windows: npx requires cmd /c wrapper — Update your MCP config to use "command": "cmd" with "args": ["/c", "npx", "-y", "@one-source/mcp@latest"]. Claude Code's /doctor command can diagnose this.

npx hangs with no output — That's normal in stdio mode. Use --http for an HTTP server.

Port already in use — Specify a different port: npx -y @one-source/mcp@latest --http --port=8080

Links

• GitHub Repository
• OneSource Documentation
• Report an Issue

License

Apache 2.0