Coldstar MCP Server

Secure signing infrastructure for AI agents on Solana. FairScore reputation gating prevents rogue agents from draining wallets.

The Problem

AI agents are getting access to crypto wallets for payments, DeFi, and autonomous trading. But an agent can be tricked -- prompt injection, compromised tool calls, or hallucinated addresses can cause it to send funds to a scam wallet. There is no guardrail between "agent decides to send" and "funds are gone."

The Solution

Coldstar MCP intercepts every outbound transaction and checks the recipient's on-chain reputation via FairScore. Low-reputation wallets are blocked. Medium-reputation wallets trigger warnings. Only verified, high-reputation addresses pass through cleanly.

The validate_transaction tool is the kill switch. Any AI agent using Coldstar will automatically refuse to send funds to wallets with Bronze-tier reputation -- even if the agent itself has been compromised.

8 Tools

| Tool | Description | |------|-------------| | check_reputation | Check FairScore reputation of any Solana wallet (score 0-100, tier, badges) | | get_token_price | Real-time token prices via Pyth Network oracle | | get_swap_quote | Jupiter DEX swap quotes with best routes across all Solana DEXes | | check_wallet_balance | SOL and SPL token balances for any wallet | | validate_transaction | Pre-flight safety check -- reputation gate before any transfer | | list_supported_tokens | All supported tokens with mint addresses | | get_portfolio | Full portfolio with USD values (balances + Pyth prices) | | estimate_swap_cost | Total swap cost analysis including price impact and fees |

Install

npm install -g coldstar-mcp

Or run directly:

npx coldstar-mcp

Configure

Claude Desktop / Claude Code

Add to your MCP settings:

{
  "mcpServers": {
    "coldstar": {
      "command": "npx",
      "args": ["-y", "coldstar-mcp"],
      "env": {
        "SOLANA_RPC_URL": "https://api.mainnet-beta.solana.com",
        "FAIRSCORE_API_KEY": ""
      }
    }
  }
}

Cursor / Windsurf / Other MCP Clients

Same configuration format -- just add the coldstar entry to your MCP config.

Environment Variables

| Variable | Default | Description | |----------|---------|-------------| | SOLANA_RPC_URL | https://api.mainnet-beta.solana.com | Solana RPC endpoint | | FAIRSCORE_API_URL | https://api2.fairscale.xyz | FairScale API base URL | | FAIRSCORE_API_KEY | (empty) | Optional FairScale API key |

Security Model

Reputation Gating

Every outbound transfer is gated by FairScore reputation tiers:

| Tier | Score | Action | Transfer Limit | |------|-------|--------|----------------| | Bronze | 0-19 | BLOCK | Blocked | | Silver | 20-39 | WARN | 10 SOL max | | Gold | 40-59 | Allow | 100 SOL max | | Platinum | 60-79 | Allow | 500 SOL max | | Diamond | 80-100 | Allow | Unlimited |

How It Protects Agents

1. Agent receives instruction to send 50 SOL to an address
2. Agent calls validate_transaction with the recipient address
3. Coldstar checks FairScore -- recipient has a score of 12 (Bronze)
4. Transaction is BLOCKED -- agent receives clear "not allowed" response
5. Agent refuses the transaction and reports the issue

The agent never needs to understand scam detection. Coldstar handles it at the infrastructure layer.

What Coldstar Does NOT Do

• It does not hold private keys (that is the air-gapped USB wallet)
• It does not sign transactions (signing is offline)
• It does not broadcast transactions (that is the user's choice)
• It only provides read operations and safety checks

This is a read-only security layer. The worst case if Coldstar is compromised is that it returns incorrect reputation data -- it can never move funds.

Example Usage

Validate Before Sending

Agent: I need to send 5 SOL to 7xKXtg2CW87d97TXJSDpbD5jBkheTqA83TZRuJosgAsU

> validate_transaction(recipient="7xKXtg...", amount=5, token="SOL")

Result: {
  "allowed": false,
  "tier": "Bronze",
  "fairscore": 8.5,
  "warnings": ["BLOCKED: Recipient has Bronze reputation (score: 8.5). Transaction denied."],
  "recommendation": "Transaction should be rejected"
}

Agent: I cannot complete this transfer. The recipient wallet has a Bronze reputation
score of 8.5/100 which indicates high risk. The transaction has been blocked by
Coldstar's reputation gating system.

Check Portfolio

> get_portfolio(wallet_address="YourWa11etAddressHere...")

Result: {
  "total_value_usd": 1523.41,
  "holdings": [
    { "symbol": "SOL", "amount": 10.5, "price_usd": 130.25, "value_usd": 1367.63 },
    { "symbol": "USDC", "amount": 155.78, "price_usd": 1.0, "value_usd": 155.78 }
  ]
}

Architecture

AI Agent (Claude, GPT, etc.)
    |
    v
Coldstar MCP Server (this package)
    |
    +---> FairScale API (reputation scoring)
    +---> Pyth Network (price oracles)
    +---> Jupiter Aggregator (DEX quotes)
    +---> Solana RPC (balances, token accounts)
    |
    v
Coldstar Air-Gapped Wallet (offline signing)

Target Integration Partners

• Phantom -- Wallet-level reputation gating
• Backpack -- Agent-aware wallet security
• Coinbase -- Institutional agent custody
• Anthropic -- Agent safety infrastructure
• OpenAI -- Agent payment guardrails
• Stripe -- Crypto payment validation

License

MIT