MCP adapter setup

What you will learn

How the MCP adapter exposes ISCL crypto operations to AI assistants
How to configure Claude Desktop and Cursor for Clavion
How to invoke tools like transfers, swaps, and balance checks
Full parameter reference for all six MCP tools

Overview

The MCP (Model Context Protocol) adapter exposes ISCL’s crypto operations as MCP tools that AI assistants can invoke. When Claude Desktop or Cursor calls a tool like clavion_transfer, the adapter constructs a TxIntent, sends it through the full ISCL pipeline (policy, preflight, approval, signing, broadcast), and returns the result.

Available tools

Tool Name	Action	Description
`clavion_transfer`	`transfer`	Transfer ERC-20 tokens
`clavion_transfer_native`	`transfer_native`	Transfer native ETH
`clavion_approve`	`approve`	Approve ERC-20 spending allowance
`clavion_swap`	`swap_exact_in`	Swap tokens via DEX
`clavion_balance`	(read-only)	Check token balance
`clavion_tx_status`	(read-only)	Look up transaction receipt

Prerequisites

Before setting up the MCP adapter, ensure you have:

ISCL Core running on localhost:3100
A wallet address imported into the ISCL keystore
RPC configured for your target chain(s)
Node.js 20+
An MCP client (Claude Desktop, Cursor, or compatible IDE)

Setup

Build the MCP adapter

cd /path/to/clavion
npm install
npm run build

The MCP adapter is built as part of the monorepo. The entry point is at packages/adapter-mcp/dist/index.js.

Configure your MCP client

Claude Desktop

Add the Clavion MCP server to your Claude Desktop configuration file.

// File: ~/Library/Application Support/Claude/claude_desktop_config.json
{
  "mcpServers": {
    "clavion": {
      "command": "node",
      "args": ["/path/to/clavion/packages/adapter-mcp/dist/index.js"],
      "env": {
        "ISCL_API_URL": "http://127.0.0.1:3100",
        "ISCL_WALLET_ADDRESS": "0xYourWalletAddress"
      }
    }
  }
}

Replace /path/to/clavion with the absolute path to your Clavion repository, and 0xYourWalletAddress with the wallet address imported into your keystore.

You must restart Claude Desktop after modifying the config file for changes to take effect.

Cursor

For Cursor IDE, add the MCP server via Cursor’s settings:

Open Cursor Settings (Cmd+, on macOS)
Search for “MCP” or navigate to the MCP configuration section
Add a new MCP server with the following configuration:

{
  "name": "clavion",
  "command": "node",
  "args": ["/path/to/clavion/packages/adapter-mcp/dist/index.js"],
  "env": {
    "ISCL_API_URL": "http://127.0.0.1:3100",
    "ISCL_WALLET_ADDRESS": "0xYourWalletAddress"
  }
}

Replace /path/to/clavion with the absolute path to your Clavion repository, and 0xYourWalletAddress with the wallet address imported into your keystore.

Start ISCL Core

The MCP adapter connects to a running ISCL Core instance. Start it in a terminal:

# Minimal (Base chain)
ISCL_RPC_URL_8453=https://mainnet.base.org npm run dev

# With web approval (recommended for interactive use)
ISCL_APPROVAL_MODE=web ISCL_RPC_URL_8453=https://mainnet.base.org npm run dev

Verify it’s running:

curl http://localhost:3100/v1/health

Use ISCL_APPROVAL_MODE=web and keep the approval dashboard open in a browser tab. When Claude or Cursor requests a transaction, you will see it appear in the dashboard for approval.

Use the tools

Once configured, your AI assistant can invoke Clavion tools directly.

Example: Transfer tokens

Ask Claude: “Send 100 USDC to 0xRecipientAddress on Base”

Claude will call clavion_transfer with:

{
  "wallet": "0xYourWalletAddress",
  "asset": {
    "kind": "erc20",
    "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "symbol": "USDC",
    "decimals": 6
  },
  "to": "0xRecipientAddress",
  "amount": "100000000",
  "chainId": 8453
}

Example: Check balance

Ask Claude: “What’s my USDC balance?”

Claude will call clavion_balance with the wallet and token addresses.

Example: Swap tokens

Ask Claude: “Swap 0.1 WETH for USDC on Base”

Claude will call clavion_swap with the appropriate parameters.

Tool parameters

Full parameter reference for each MCP tool.

clavion_transfer

Parameter	Type	Required	Description
`wallet`	string	Yes	Sender address (0x + 40 hex)
`asset.kind`	string	Yes	Always `"erc20"`
`asset.address`	string	Yes	Token contract address
`asset.symbol`	string	No	Token symbol (e.g., “USDC”)
`asset.decimals`	number	No	Token decimals
`to`	string	Yes	Recipient address
`amount`	string	Yes	Amount in base units (wei)
`chainId`	number	No	Chain ID (default: 8453)
`maxGasWei`	string	No	Max gas limit in wei

clavion_transfer_native

Parameter	Type	Required	Description
`wallet`	string	Yes	Sender address
`to`	string	Yes	Recipient address
`amount`	string	Yes	Amount in wei
`chainId`	number	No	Chain ID (default: 8453)
`maxGasWei`	string	No	Max gas limit in wei

clavion_swap

Parameter	Type	Required	Description
`wallet`	string	Yes	Wallet performing the swap
`router`	string	Yes	DEX router address
`assetIn`	object	Yes	Input token (selling)
`assetOut`	object	Yes	Output token (buying)
`amountIn`	string	Yes	Exact input amount in base units
`minAmountOut`	string	Yes	Minimum output (slippage floor)
`slippageBps`	number	No	Slippage in basis points (default: 100 = 1%)
`provider`	string	No	`"uniswap_v3"` or `"1inch"`
`chainId`	number	No	Chain ID (default: 8453)

clavion_balance

Parameter	Type	Required	Description
`wallet`	string	Yes	Wallet address to check
`token`	string	Yes	ERC-20 token contract address
`chainId`	number	No	Chain ID (default: 8453)

clavion_tx_status

Parameter	Type	Required	Description
`txHash`	string	Yes	Transaction hash (0x + 64 hex)

clavion_approve

Parameter	Type	Required	Description
`wallet`	string	Yes	Owner address (0x + 40 hex)
`asset.kind`	string	Yes	Always `"erc20"`
`asset.address`	string	Yes	Token contract address
`asset.symbol`	string	No	Token symbol
`asset.decimals`	number	No	Token decimals
`spender`	string	Yes	Spender address to approve
`amount`	string	Yes	Allowance amount in base units
`chainId`	number	No	Chain ID (default: 8453)
`maxGasWei`	string	No	Max gas limit in wei

Approval modes

How the user approves transactions depends on the ISCL Core approval mode:

Mode	Behavior	Best For
`cli`	Readline prompt in the ISCL Core terminal	Development, single-user
`web`	Pending in web dashboard at `/approval-ui`	Interactive use, multi-tool
`auto`	Auto-approved (no human confirmation)	Testing only

Recommended for MCP: Use ISCL_APPROVAL_MODE=web and keep the approval dashboard open in a browser tab. When Claude requests a transaction, you will see it appear in the dashboard for approval.

Multi-chain configuration

The chainId parameter on each tool defaults to 8453 (Base). To use other chains, ensure ISCL Core has the corresponding RPC URL configured:

ISCL_RPC_URL_1=https://eth-mainnet.alchemy.com/v2/KEY \
ISCL_RPC_URL_8453=https://base-mainnet.alchemy.com/v2/KEY \
npm run dev

Then ask Claude to specify the chain: “Send 1 ETH to 0xAlice on Ethereum mainnet”

Supported chains: Ethereum (1), Optimism (10), Arbitrum (42161), Base (8453). Each chain requires its own ISCL_RPC_URL_<chainId> environment variable.

Troubleshooting

Tools don’t appear in Claude Desktop

Verify the config file path is correct for your OS
Check that the command path points to the built JS file
Restart Claude Desktop after config changes
Check Claude Desktop logs for MCP server startup errors

”ISCL Core not reachable”

The MCP adapter checks ISCL Core health on startup. Ensure Core is running:

curl http://localhost:3100/v1/health

Approval hangs

If using cli mode, check the ISCL Core terminal for the readline prompt. If using web mode, open http://localhost:3100/approval-ui and approve the pending request.

Schema validation errors

The MCP adapter validates parameters using Zod schemas. Ensure:

Addresses are checksummed 0x-prefixed (40 hex chars)
Amounts are string integers (no decimals, no “0x” prefix)
Chain IDs are positive integers

Security notes

The MCP adapter runs in Domain A (untrusted). It cannot access private keys directly.

All transactions go through the full ISCL pipeline: policy, preflight, approval, signing.
The adapter communicates with ISCL Core over localhost HTTP only.
Tool descriptions inform the AI about security properties (policy enforcement, human approval).
No signing material is ever exposed to the MCP transport layer.

References

Adapter Development Tutorial — How the MCP adapter was built
API Reference — Underlying API endpoints
Configuration Reference — Environment variables
MCP Protocol Specification — Official MCP documentation

Walkthroughs

Advanced

MCP adapter setup

What you will learn

Overview

Available tools

Prerequisites

Setup

Tool parameters

clavion_transfer

clavion_transfer_native

clavion_swap

clavion_balance

clavion_tx_status

clavion_approve

Approval modes

Multi-chain configuration

Troubleshooting

Tools don’t appear in Claude Desktop

”ISCL Core not reachable”

Approval hangs

Schema validation errors

Security notes

References

Walkthroughs

Advanced

​What you will learn

​Overview

​Available tools

​Prerequisites

​Setup

​Tool parameters

​clavion_transfer

​clavion_transfer_native

​clavion_swap

​clavion_balance

​clavion_tx_status

​clavion_approve

​Approval modes

​Multi-chain configuration

​Troubleshooting

​Tools don’t appear in Claude Desktop

​”ISCL Core not reachable”

​Approval hangs

​Schema validation errors

​Security notes

​References

What you will learn

Overview

Available tools

Prerequisites

Setup

Tool parameters

clavion_transfer

clavion_transfer_native

clavion_swap

clavion_balance

clavion_tx_status

clavion_approve

Approval modes

Multi-chain configuration

Troubleshooting

Tools don’t appear in Claude Desktop

”ISCL Core not reachable”

Approval hangs

Schema validation errors

Security notes

References