Mcp Server For Ai To Blockchain Interactions — Balances, Swaps, Transfers, Gas, Prices. Non Custodial. Multi Chain.

@y0exchange/mcp

Let AI agents trade crypto. Non-custodial. Multi-chain. One MCP server.

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What is this?

@y0exchange/mcp is a Model Context Protocol server that gives AI agents real-time access to DeFi — balances, prices, gas, swap quotes, transaction history, and the ability to execute swaps and transfers.

Connect it to Claude, ChatGPT, or any MCP-compatible AI client. Your users talk to AI, AI talks to the blockchain.

User  →  AI Agent  →  @y0exchange/mcp  →  Blockchain
                            ↓
                     y0 Signing Service (user signs on their device)

Non-custodial by design. y0 never touches private keys. Write operations build unsigned transactions — the user always signs on their own device.

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Quick Start

1. Get your API key

Sign in at app.y0.exchange → API Keys → copy your key.

2. Add connector (recommended)

The simplest way — works on Claude Desktop, claude.ai, Claude Mobile, and ChatGPT:

1. Open your AI app → Settings → Connectors → Add custom connector
2. Name: y0
3. URL: https://mcp.y0.exchange/mcp?key=YOUR_API_KEY
4. Save — done!

No installs, no config files, no terminal. The API key links to your wallet — the AI agent automatically knows your address and permissions.

For developer IDEs (Cursor, Windsurf)

Add to your MCP config (e.g. .cursor/mcp.json):

{
  "mcpServers": {
    "y0": {
      "command": "npx",
      "args": ["-y", "@y0exchange/mcp"],
      "env": {
        "Y0_API_KEY": "y0_your_api_key_here"
      }
    }
  }
}

Claude Code

claude mcp add --transport http y0 https://mcp.y0.exchange/mcp?key=YOUR_API_KEY

Any MCP client (stdio)

Y0_API_KEY=y0_... npx @y0exchange/mcp

The server communicates over stdio — compatible with any MCP client.

Read-only mode

Without Y0_API_KEY, read-only tools (balances, prices, gas, quotes, history) still work. Omit the key to experiment without an account.

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Remote Server (HTTP)

The hosted remote server at mcp.y0.exchange powers the connector approach above. You can also self-host it.

Self-host the remote server

# Build
pnpm --filter @y0exchange/mcp build

# Run
pnpm --filter @y0exchange/mcp start:remote

# Or with Docker
docker build -f mcp/Dockerfile -t y0-mcp-remote .
docker run -p 3100:3100 \
  -e SIGNING_SERVICE_URL=https://api.y0.exchange \
  -e ZEROX_API_KEY=your_key \
  y0-mcp-remote

The remote server exposes:

• POST /mcp — Streamable HTTP MCP endpoint
• GET /health — health check

Environment variable PORT controls the listening port (default: 3100).

How it differs from stdio

	stdio (npx)	Remote (HTTP)
Runs on	User's machine	Your server
Transport	stdin/stdout	Streamable HTTP
Works on mobile	No	Yes
Works on claude.ai	No	Yes
Auth	Y0_API_KEY env var	?key= in URL or Authorization header
Deployment	None (npm)	Docker / any Node.js host

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Tools

Read-only — work out of the box, no API keys required

Tool	Description
get_balance	Native + ERC-20 token balances for any wallet
get_portfolio	Aggregated portfolio across all chains with USD values
get_price	Real-time token prices with 24h change
get_quote	Swap quotes with routing preview, fees, and gas estimate
get_gas	Gas prices across chains with USD cost estimates
get_history	Transaction history with smart classification

Write — requires Y0_API_KEY

Tool	Description
swap	Build unsigned swap tx → user approves on device
send	Build unsigned transfer tx → user approves on device

Write tools use your API key to identify your wallet. The AI agent never needs to ask for your address — it's resolved automatically from the key.

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Supported Chains

Chain	ID	Status
Ethereum	1	Production
BNB Chain	56	Production
Arbitrum	42161	Production
Base	8453	Production
Polygon	137	Production

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Configuration

All configuration is via environment variables. None are required for read-only tools.

Core

Variable	Description	Default
Y0_API_KEY	Your y0 API key (required for swap/send)	—
SIGNING_SERVICE_URL	y0 Signing Service endpoint	https://api.y0.exchange

Swap Providers

Variable	Description
ZEROX_API_KEY	0x swap API key (tried first)
ONEINCH_API_KEY	1inch swap API key (fallback)

Block Explorers (for get_history)

Variable	Description
ETHERSCAN_API_KEY	Etherscan API key
BSCSCAN_API_KEY	BSCScan API key
ARBISCAN_API_KEY	Arbiscan (falls back to Etherscan key)
BASESCAN_API_KEY	BaseScan (falls back to Etherscan key)
POLYGONSCAN_API_KEY	PolygonScan (falls back to Etherscan key)

Pricing

Variable	Description
COINGECKO_API_KEY	CoinGecko Pro key (optional, free tier works)

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How Swaps Work

1. User says: "Swap 1 ETH to USDC"

2. AI calls get_quote → shows price, fees, slippage

3. User confirms → AI calls swap (no wallet address needed — resolved from API key)

4. MCP authenticates with y0 Signing Service via Y0_API_KEY
   → builds unsigned transaction
   → sends push notification to user's mobile app

5. User reviews and signs on their device (biometric + wallet)

6. Transaction executes on-chain

Your keys never leave your device. The MCP server and y0 Signing Service only handle unsigned transaction payloads.

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Example Conversations

"What's my portfolio worth?"

AI calls get_portfolio → returns breakdown by chain, token allocations, total USD value

"How much gas would a swap cost on Base right now?"

AI calls get_gas with chainId 8453 → returns gas price + USD estimates for different tx types

"Swap 500 USDC to ETH on Arbitrum"

AI calls get_quote → shows expected output → user confirms → swap builds unsigned tx → user signs

"Send 0.5 ETH to vitalik.eth"

AI calls send → builds unsigned transfer → user signs on device

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Skill: Smarter DeFi Workflows

The MCP server gives Claude access to DeFi tools. The y0 DeFi Skill teaches Claude how to use them well — checking balances before swaps, warning about gas costs, recommending optimal chains, and following DeFi best practices automatically.

What it adds

• Pre-swap safety checks (balance, gas, slippage recommendations)
• Portfolio analysis with concentration risk warnings
• Cross-chain gas comparison and routing suggestions
• Confirmation gates before any write operation
• Domain expertise: stablecoin slippage, native token reserves, test transaction recommendations

Install the skill

Claude.ai:

1. Download skill.zip
2. Go to Settings → Capabilities → Skills
3. Click Upload skill and select the downloaded skill.zip
4. Make sure your y0 MCP connector is also connected

Claude Code:

# Place the skill folder in your Claude Code skills directory
cp -r skill/ ~/.claude/skills/y0-defi-assistant/

Verify it works

Ask Claude: "Check my crypto portfolio" — it should automatically call get_portfolio, present a clear breakdown, and note any concentration risks or gas optimization opportunities.

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For B2B Partners

Building an AI-powered trading product? y0 provides the infrastructure:

• MCP server — this package, plug into any AI agent
• Signing UI — white-label transaction approval widget
• Signing Service — managed backend for transaction building + lifecycle
• B2B Portal — API keys, usage dashboards, billing

Get in touch to set up your integration.

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Architecture

┌───────────────────────────────────────────────────────────┐
│                    AI Agents                               │
│  Claude Desktop / Claude Code / Cursor / GPT / custom     │
│  claude.ai / Claude Mobile                                │
└──────────┬───────────────────────────────┬────────────────┘
           │ stdio (local)                 │ HTTP (remote)
           │ npx @y0exchange/mcp           │ .../mcp?key=YOUR_API_KEY
           ▼                               ▼
┌──────────────────────────────────────────────────────────┐
│                   @y0exchange/mcp                         │
│                                                          │
│  ┌─────────────────┐  ┌──────────────────┐               │
│  │   Read Tools     │  │   Write Tools    │               │
│  │                  │  │                  │               │
│  │  get_balance     │  │  swap ─────────────► y0 Signing  │
│  │  get_portfolio   │  │  send ─────────────► Service     │
│  │  get_price       │  │                  │               │
│  │  get_quote       │  └──────────────────┘               │
│  │  get_gas         │                                     │
│  │  get_history     │                                     │
│  └────────┬─────────┘                                     │
└───────────┼───────────────────────────────────────────────┘
            │
   ┌────────▼─────────┐
   │   Blockchain RPCs │
   │   CoinGecko API   │
   │   0x / 1inch APIs │
   │   Block Explorers │
   └───────────────────┘

Mobile / Web (claude.ai, Claude Mobile):
  Uses remote HTTP server — no local process needed.

Desktop / CLI (Claude Desktop, Claude Code, Cursor):
  Can use either stdio (npx) or remote HTTP.

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Development

# Clone the monorepo
git clone https://github.com/y0exchange/y0exchange.git
cd y0exchange

# Install dependencies
pnpm install

# Build
pnpm --filter @y0exchange/mcp build

# Run stdio server (local dev)
pnpm --filter @y0exchange/mcp start

# Run remote HTTP server (local dev)
pnpm --filter @y0exchange/mcp start:remote

# Watch mode (rebuilds on change)
pnpm --filter @y0exchange/mcp dev

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License

MIT — use it freely in your products. See LICENSE for details.

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Built by y0.exchange — AI-native DeFi infrastructure