PACT MCP Server

MCP server for PACT Protocol — trustless escrow and payment channels for AI agents on Arbitrum One.

Built for the Arbitrum Vibekit ecosystem. Enables any MCP-compatible agent to create escrow agreements, open payment channels, and settle transactions with other agents — all on-chain, no trust required.

Install

npm install pact-mcp-server

Or run directly:

npx pact-mcp-server

Or from source:

git clone https://github.com/praxisagent/pact-vibekit-plugin.git
cd pact-vibekit-plugin
npm install
npm run build
npm start

What It Does

Escrow (PactEscrow v2) — Lock PACT tokens in a smart contract. Recipient submits work (with SHA256 hash). Creator has a dispute window to accept or challenge. If no dispute, anyone can release funds after the window expires. If deadline passes without work, creator reclaims. Optional third-party arbitration.

Payment Channels — Open a channel once, exchange unlimited micropayments off-chain via EIP-712 signed state updates, settle on-chain when done. Two transactions total regardless of payment count.

Tools

Read (no wallet needed)

Tool	Description
pact_get_info	Protocol overview with live escrow/channel stats
pact_get_escrow	Get escrow pact details by ID (status, deadline, work hash, releaseability)
pact_get_channel	Get payment channel details by ID (agents, balances, state)
pact_get_balance	PACT token balance for any address

Write (returns unsigned transactions for the agent to sign)

Tool	Description
pact_build_approve_token	Approve PACT tokens for escrow or channel contract
pact_build_create_escrow	Create new escrow (multi-step: approve + create)
pact_build_submit_work	Submit work evidence hash (recipient)
pact_build_approve_escrow	Accept work and release tokens (creator)
pact_build_dispute_escrow	Dispute submitted work (creator, within dispute window)
pact_build_release_escrow	Release funds after dispute window (anyone)
pact_build_reclaim_escrow	Reclaim tokens after expired deadline (creator)
pact_build_open_channel	Open payment channel (multi-step: approve + open)
pact_build_fund_channel	Fund your side of channel (multi-step: approve + fund)

Connect to Your Agent

Environment variables (optional):

ARBITRUM_RPC_URL=https://arb1.arbitrum.io/rpc  # Defaults to public RPC
PORT=3012                                       # Defaults to 3012

HTTP endpoint: http://localhost:3012/mcp

MCP client config (e.g., Vibekit mcp.json):

{
  "mcpServers": {
    "pact": {
      "url": "http://localhost:3012/mcp"
    }
  }
}

STDIO (Claude Desktop claude_desktop_config.json):

{
  "mcpServers": {
    "pact": {
      "command": "npx",
      "args": ["pact-mcp-server"]
    }
  }
}

Transaction Plan Format

Write tools return unsigned transaction calldata — the calling agent signs and broadcasts. No private keys ever touch the MCP server.

{
  "chainId": 42161,
  "to": "0x220B97972d6028Acd70221890771E275e7734BFB",
  "data": "0x...",
  "value": "0",
  "description": "Create escrow: 500 PACT to 0xRecipient, deadline in 72h",
  "steps": [
    { "to": "0x809c...", "data": "0x...", "description": "Step 1: Approve 500 PACT" },
    { "to": "0x220B...", "data": "0x...", "description": "Step 2: Create escrow" }
  ]
}

When steps is present, submit each step sequentially.

Contracts (Arbitrum One)

Contract	Address
PACT Token	0x809c2540358E2cF37050cCE41A610cb6CE66Abe1
PactEscrow v2	0x220B97972d6028Acd70221890771E275e7734BFB
PactPaymentChannel	0x5a9D124c05B425CD90613326577E03B3eBd1F891

Security

• No private keys. Write tools return unsigned transactions. The agent's wallet handles signing.
• No max approvals. Approve tools take exact amounts.
• Read-only RPC. The server only reads chain state. No transactions are sent server-side.
• Validated inputs. All parameters are Zod-validated before processing.

Microgrants

PACT Protocol funds builders. Up to 10,000 PACT for integrations, escrow usage, and LP provision. Apply at dopeasset.com/grants.

License

MIT

Links

• PACT Protocol
• npm package
• GitHub
• Grants Program
• Vibekit PR #572