b402 Private DeFi

Private DeFi for AI agents. Shield tokens into a Railgun ZK privacy pool, swap privately, lend into Morpho vaults for yield, and bridge cross-chain via LI.FI...

Security Scan

The skill's DeFi purpose is plausible, but the runtime instructions and installer make persistent modifications (writing a wallet file, patching a desktop agent config, registering a server) and rely on running npm code fetched at install-time — actions that are beyond a simple integration and warrant caution.

Purpose & Capability

Requiring node/npx and a private key is coherent for a DeFi SDK that must sign transactions. The declared npm package (b402-mcp) aligns with the described MCP server. However, the SKILL.md explicitly says the installer will 'patch your Claude Desktop config' and 'register the MCP server' which are not intrinsic to 'shield/swap/lend/bridge' operations and suggest broader system integration.

Instruction Scope

The SKILL.md instructs running npx b402-mcp@latest which will generate ~/.b402/wallet.json, patch Claude Desktop config, and register an MCP server. Those steps read/write user home files and modify another agent's configuration — actions outside the minimal scope of a DeFi SDK and that grant long-lived capabilities and persistence.

Install Mechanism

Installation uses an npm package (b402-mcp) which is a traceable registry source (moderate risk). However, the recommended npx @latest pattern downloads and runs whatever is published at runtime, which increases supply-chain risk compared to installing a pinned, reviewed release.

Credentials

The skill only declares a single required credential (WORKER_PRIVATE_KEY), which is appropriate for signing transactions. But the installer also writes a wallet file to disk (~/.b402/wallet.json) and patches desktop config — this implies storing private keys locally and giving the tool persistent access to the agent environment. The SKILL.md does not clarify whether the wallet file is encrypted, whether the env key is copied there, or why both a generated wallet and an env private key are needed.

Persistence & Privilege

The skill will persist credentials to disk and modify another agent's (Claude Desktop) configuration and 'register' an MCP server. Modifying other agent configs and registering services increases the blast radius and is outside the typical scope of a single-purpose skill.

What to consider before installing

This skill is plausible for private DeFi, but it requires strong trust before you install or run it. Key things to consider before installing: 1) It asks for WORKER_PRIVATE_KEY — feeding a raw private key to any tool gives it full control over funds; prefer using ephemeral accounts or hardware signing if possible. 2) The installer (npx b402-mcp@latest) will create ~/.b402/wallet.json — confirm whether that file stores an unencrypted private key. 3) The installer will 'patch your Claude Desktop config' and 'register the MCP server' — understand exactly what config is changed and what network endpoints the MCP server opens (is it locally bound only, or exposed remotely?). 4) npx @latest runs code fetched at install-time: review the npm package source (b402-mcp) and the referenced GitHub repo before running; prefer pinned versions and inspect the package contents. 5) If you plan to proceed, test in an isolated environment (VM/container) with small amounts or a throwaway account first. Ask the publisher for: (a) a clear explanation of what 'patch Claude Desktop config' does, (b) whether ~/.b402/wallet.json is encrypted, (c) whether WORKER_PRIVATE_KEY is strictly required or optional, (d) the exact network interfaces/ports the MCP server binds to and whether it requires authentication, and (e) a pinned package release and reproducible build/source link so you can audit the code.

b402 — Private DeFi for AI Agents

Shield. Swap. Lend. Bridge. All private. All gasless.

b402 wraps Railgun's ZK privacy pool with an agent-friendly SDK and MCP server. On-chain observers see "RelayAdapt called a DEX" — not your wallet, not your strategy.

Install

npx b402-mcp@latest --claude

This generates a wallet at ~/.b402/wallet.json, patches your Claude Desktop config, and registers the MCP server. Fund the wallet with USDC on Base to start.

Tools

Tool	What it does
check_pool_balance	Show shielded balances, wallet state, vault positions
shield_usdc	Move USDC into the Railgun privacy pool (gasless)
private_swap	Swap tokens inside the pool via ZK proof (USDC↔WETH, etc.)
lend_privately	Deposit into Morpho vault from pool (~4-8% APY)
redeem_privately	Withdraw from Morpho vault back to pool
cross_chain_privately	Private cross-chain transfer or swap via LI.FI (Base→Arb, etc.)
get_swap_quote	Preview swap rates without executing
run_strategy	Multi-step: swap + lend + reserve in one call

Example prompts

• "Check my privacy pool balance"
• "Shield 5 USDC into the pool"
• "Swap 2 USDC to WETH privately"
• "Privately send 1 USDC to 0xABC... on Arbitrum"
• "Private cross-chain swap: 1 USDC from pool to ARB on Arbitrum, to 0xABC..."
• "Lend 10 USDC in the steakhouse vault"
• "Run a yield strategy: 30% WETH, 50% lend, 20% reserve"

How it works

Agent prompt → MCP tool call → b402-sdk
  → Railgun ZK proof (client-side, 10-30s)
  → RelayAdapt atomic tx (unshield → DeFi op → reshield)
  → On-chain: only RelayAdapt visible. No wallet linked.

Cross-chain: LI.FI routes through ~30 bridges + ~20 DEXes. Source and destination are unlinkable.

Supported chains

Chain	ID	Privacy pool	Cross-chain
Base	8453	Yes (0% fee)	Source + dest
Arbitrum	42161	Yes (0% fee)	Dest only (v1)
BSC	56	Yes (0% fee)	Dest only (v1)

SDK usage (for builders)

import { B402 } from '@b402ai/sdk'

const b402 = new B402({ privateKey: process.env.WORKER_PRIVATE_KEY! })

// Shield into privacy pool (gasless)
await b402.shieldFromEOA({ token: 'USDC', amount: '10' })

// Private swap inside pool
await b402.privateSwap({ from: 'USDC', to: 'WETH', amount: '5' })

// Private cross-chain (LI.FI routing)
await b402.privateCrossChain({
  toChain: 'arbitrum',
  fromToken: 'USDC',
  toToken: 'ARB',
  amount: '1',
  destinationAddress: '0x...',
})

// Private lend (Morpho vaults, 4-8% APY)
await b402.privateLend({ amount: '10', vault: 'steakhouse' })

Links

• SDK: npmjs.com/package/@b402ai/sdk
• MCP: npmjs.com/package/b402-mcp
• Starter: github.com/b402-ai/b402-starter
• Agent template: github.com/b402-ai/b402-agent-starter