eth_sendTransaction · Privy MCP Server MCP: Risk & Policy

WHAT IT DOES

What eth_sendTransaction does on Privy MCP Server

AI agents use eth_sendTransaction to commit financial operations through Privy MCP Server — usually the final step of a payment, billing, or trading workflow. A call moves real money.

WHY IT NEEDS A POLICY

Why eth_sendTransaction needs a policy

eth_sendTransaction signs AND broadcasts a transaction to the blockchain, making it irreversible once confirmed. This can transfer ETH or tokens, interact with DeFi protocols, or execute any on-chain financial operation. Since transactions on public blockchains are irreversible and can move funds, this falls under Financial (most severe).

From the tool's definition Sign and broadcast a transaction to the blockchain network

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

eth_sendTransaction Approval-gated

Any call to eth_sendTransaction is blocked until a human approves it. The rest of the server keeps working.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "eth_sendTransaction": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}

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PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Privy MCP Server, so you can run agents against it safely.

FAQ

Questions about eth_sendTransaction

What does the eth_sendTransaction tool do? +

Sign and broadcast a transaction to the blockchain network. It is categorised as a Financial tool in the Privy MCP Server MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on eth_sendTransaction? +

Register the Privy MCP Server MCP server in PolicyLayer and add a rule for eth_sendTransaction: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Privy MCP Server. Nothing to install.

What risk level is eth_sendTransaction? +

eth_sendTransaction is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit eth_sendTransaction? +

Yes. Add a rate_limit block to the eth_sendTransaction rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block eth_sendTransaction completely? +

Set action: deny in the PolicyLayer policy for eth_sendTransaction. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides eth_sendTransaction? +

eth_sendTransaction is provided by the Privy MCP Server MCP server (privy-io/privy-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.