Fuse MCP Server

Model Context Protocol server for the Fuse blockchain. Lets AI agents (Claude, Cursor, Gemini, ...) read Fuse on-chain data, submit account-abstracted transactions, deploy contracts, and operate Fusebox APIs through one standard tool interface.

Two ways to use it:

1. Hosted at https://mcp.fuse.io/mcp — free, read-only, configured with Fuse's API keys. No setup beyond pointing your agent at the URL.
2. Self-hosted via Docker or node dist/index.js — required for any write tool (you must control the private key) and for higher rate limits.

Three back-ends, layered:

• viem JSON-RPC — chain primitives any public node can serve, plus EOA writes (send FUSE, ERC-20 transfers, generic contract calls, contract deployment, EIP-191 / EIP-712 signing).
• Fusebox Web SDK — value-added read APIs (token prices, staking, portfolio, UserOp history) and ERC-4337 smart-account writes via UserOperations (optionally gasless via the Fuse paymaster).
• Fusebox REST APIs — direct access to Notification, Smart Wallet, Trade, and Explorer endpoints.

---

Quick install for AI agents (hosted at mcp.fuse.io)

The hosted endpoint speaks the Streamable HTTP transport at https://mcp.fuse.io/mcp. All read tools are enabled; write tools are not (they need a server-side private key — see Self-hosting for writes below).

Claude Code

claude mcp add fuse --transport http https://mcp.fuse.io/mcp

To remove later: claude mcp remove fuse.

Cursor

Settings → MCP → Add new server, or edit ~/.cursor/mcp.json:

{
  "mcpServers": {
    "fuse": {
      "url": "https://mcp.fuse.io/mcp"
    }
  }
}

Claude Desktop

Claude Desktop currently launches MCP servers as local subprocesses, so it talks to the hosted endpoint through the mcp-remote bridge. Edit ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "fuse": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://mcp.fuse.io/mcp"]
    }
  }
}

Restart Claude Desktop.

Continue (VS Code / JetBrains)

~/.continue/config.yaml:

mcpServers:
  - name: fuse
    url: https://mcp.fuse.io/mcp

Cline / Roo Code

Add via the MCP sidebar → "Add Remote Server", URL https://mcp.fuse.io/mcp. Or edit ~/.cline/mcp_settings.json:

{
  "mcpServers": {
    "fuse": { "url": "https://mcp.fuse.io/mcp", "transport": "streamable-http" }
  }
}

Zed

~/.config/zed/settings.json:

{
  "context_servers": {
    "fuse": { "command": { "path": "npx", "args": ["-y", "mcp-remote", "https://mcp.fuse.io/mcp"] } }
  }
}

Anything else (generic Streamable HTTP client)

Endpoint: https://mcp.fuse.io/mcp Transport: Streamable HTTP (POST + optional SSE upgrade) Auth: none on the hosted endpoint (it's read-only)

---

Self-hosting for writes

The hosted endpoint deliberately runs without FUSE_PRIVATE_KEY — write tools refuse to operate. Run your own instance when you need to sign transactions, deploy contracts, or submit ERC-4337 UserOps.

Docker

docker build -t fuse-mcp-server .
docker run --rm -p 3000:3000 \
  -e MCP_TRANSPORT=http \
  -e FUSEBOX_PUBLIC_API_KEY=pk_live_... \
  -e FUSE_PRIVATE_KEY=0x... \
  -e FUSE_USE_PAYMASTER=true \
  fuse-mcp-server

Point your agent at http://127.0.0.1:3000/mcp. Same configs as above, swapping the URL.

docker-compose

Drop secrets into a .env file next to docker-compose.yml:

FUSEBOX_PUBLIC_API_KEY=pk_live_...
FUSEBOX_SECRET_API_KEY=sk_live_...
FUSE_PRIVATE_KEY=0x...
FUSE_USE_PAYMASTER=true

Then:

docker compose up -d

Node directly (stdio mode for local subprocess clients)

npm install
npm run build
FUSE_PRIVATE_KEY=0x... node dist/index.js

For Claude Desktop / any client that spawns the server as a subprocess:

{
  "mcpServers": {
    "fuse": {
      "command": "node",
      "args": ["/absolute/path/to/fuse-mcp-server/dist/index.js"],
      "env": {
        "FUSEBOX_PUBLIC_API_KEY": "pk_live_...",
        "FUSE_PRIVATE_KEY": "0x...",
        "FUSE_USE_PAYMASTER": "true"
      }
    }
  }
}

---

Tools (v0.2) — 50 total

RPC reads — 8 (no API key required)

Tool	Description
fuse_get_balance	Native FUSE or ERC-20 balance.
fuse_get_transaction	Fetch a transaction.
fuse_get_receipt	Fetch a transaction receipt.
fuse_read_contract	Call any view/pure function (ABI auto-fetched).
fuse_get_token_metadata	name / symbol / decimals / totalSupply.
fuse_get_gas_price	Current gas price + EIP-1559 fee suggestions.
fuse_resolve_ens	Resolve an ENS name (requires ENS_RPC_URL).
fuse_get_account_abstraction_info	ERC-4337 state for a smart account.

Fusebox SDK reads — 10 (requires FUSEBOX_PUBLIC_API_KEY)

fuse_list_wallet_tokens, fuse_list_wallet_nfts, fuse_get_staking_options, fuse_get_staked_tokens, fuse_get_token_price, fuse_get_token_price_change, fuse_get_token_price_history, fuse_list_supported_tokens, fuse_get_trade_quote, fuse_get_user_operations.

Fusebox REST APIs — 14 (requires FUSEBOX_PUBLIC_API_KEY; Notification also needs FUSEBOX_SECRET_API_KEY)

Notification (8): fuse_notification_{create,get,list_project,update,delete}_webhook, fuse_notification_{add,remove,list}_addresses. Smart Wallet (2): fuse_smart_wallet_authenticate, fuse_smart_wallet_get_actions. Trade (3, non-SDK): fuse_trade_indicative_price, fuse_trade_liquidity_sources, fuse_trade_price_change_over_duration. Explorer (1 generic dispatcher): fuse_explorer_query — covers all 40+ etherscan-style endpoints.

EOA writes — 7 (requires FUSE_PRIVATE_KEY)

Tool	Description
fuse_get_signer_address	Show which EOA the server controls.
fuse_send_native	Transfer native FUSE.
fuse_send_erc20	Transfer an ERC-20 (decimals auto-detected).
fuse_write_contract	State-mutating call (simulates first to surface revert reasons).
fuse_deploy_contract	Deploy from bytecode + ABI + args. Optionally waits for the receipt.
fuse_sign_message	EIP-191 (personal_sign) signature. No tx broadcast.
fuse_sign_typed_data	EIP-712 structured-data signature. No tx broadcast.

Smart-account writes (ERC-4337 UserOps) — 11 (requires FUSE_PRIVATE_KEY + FUSEBOX_PUBLIC_API_KEY)

fuse_smart_get_info, fuse_smart_transfer_{token,nft}, fuse_smart_approve_{token,nft}, fuse_smart_approve_and_call, fuse_smart_call_contract, fuse_smart_execute_batch, fuse_smart_swap_tokens, fuse_smart_stake_token, fuse_smart_unstake_token. Set FUSE_USE_PAYMASTER=true to route through the Fuse paymaster (gasless).

---

Configuration

Variable	Default	Purpose
MCP_TRANSPORT	stdio	stdio (local subprocess) or http (Streamable HTTP for hosted/Docker).
MCP_HTTP_HOST	0.0.0.0	HTTP bind host.
MCP_HTTP_PORT	3000	HTTP listen port.
MCP_HTTP_PATH	/mcp	HTTP route path.
FUSE_NETWORK	mainnet	mainnet (chain 122) or spark (testnet, chain 123).
FUSE_RPC_URL	network default	Override the JSON-RPC endpoint.
FUSE_EXPLORER_URL	network default	Override the Blockscout explorer base URL.
FUSE_ENTRYPOINT_ADDRESS	ERC-4337 v0.7 canonical	Override the EntryPoint.
ENS_RPC_URL	unset	Ethereum mainnet RPC for .eth resolution.
FUSEBOX_PUBLIC_API_KEY	unset	Public API key — required for SDK + REST + smart-account tools.
FUSEBOX_SECRET_API_KEY	unset	Secret API key (API-SECRET header). Required only by Notification API tools.
FUSEBOX_BASE_URL	SDK default	Override the SDK's Fusebox API host.
FUSEBOX_API_ORIGIN	https://api.fuse.io	Override the raw HTTP client's Fusebox API origin.
FUSE_PRIVATE_KEY	unset	32-byte hex private key for the signer. Required by every write tool. Read once at startup; never accepted as a tool argument.
FUSE_USE_PAYMASTER	false	When true, smart-account UserOps route through the Fuse paymaster (gasless).

Security model

• Key handling. Private keys live in the server's environment only. They are never accepted as tool arguments — that would leak them into the agent's conversation transcript. The server reads FUSE_PRIVATE_KEY once at startup and signs locally.
• Hosted endpoint. https://mcp.fuse.io/mcp has no FUSE_PRIVATE_KEY configured. Write tools return an actionable error pointing users to self-hosting. The Fusebox public key bundled there is rate-limited for fair sharing.
• Self-hosted production. Treat the server as a hot-wallet signer. Run it next to your application, lock down ingress, fund the EOA with the minimum FUSE you're willing to lose to a prompt-injection mishap, and prefer the paymaster (FUSE_USE_PAYMASTER=true) so the smart wallet can transact without holding gas.

---

Project layout

.
├── Dockerfile                    Multi-stage build → distroless-ish Alpine runtime, non-root user
├── docker-compose.yml            One-line local deploy
├── .dockerignore
├── package.json
├── tsconfig.json
└── src/
    ├── index.ts                  Transport dispatcher (stdio | http)
    ├── server.ts                 Builds the McpServer + ToolContext
    ├── config.ts                 Env loading
    ├── types.ts                  Shared tool types
    ├── transports/
    │   ├── stdio.ts              Local subprocess transport
    │   └── http.ts               Streamable HTTP transport + /healthz
    ├── clients/
    │   ├── rpc.ts                viem PublicClient factories
    │   ├── signer.ts             EOA signer (viem WalletClient + ethers v5 Wallet)
    │   ├── explorer.ts           Blockscout ABI fetcher
    │   ├── fusebox.ts            Fusebox SDK factories (read-only + credentialed)
    │   └── fuseboxApi.ts         Raw HTTP client for Fusebox REST APIs
    ├── lib/
    │   ├── address.ts            Address validation, ENS heuristics, hex bytes
    │   ├── erc20.ts              ERC-20 ABI (read + write)
    │   ├── units.ts              parseAmount / fetchErc20Decimals
    │   ├── format.ts             BigInt-safe JSON serialization
    │   └── userOp.ts             UserOp response → JSON-safe summary
    └── tools/
        ├── index.ts              Registry (50 tools)
        ├── *.ts                  RPC reads (8)
        ├── listWalletTokens.ts … getUserOperations.ts   Fusebox SDK reads (10)
        ├── notifications/        Fusebox Notification API (8)
        ├── smartWallets/         Fusebox Smart Wallet API (2)
        ├── tradeApi/             Fusebox Trade API non-SDK endpoints (3)
        ├── explorerApi/          Fusebox Explorer API dispatcher (1)
        ├── writes/               EOA writes (7)
        └── smart/                Smart-account writes (11)