eth_signTypedData_v4 · Privy MCP Server MCP: Risk & Policy

WHAT IT DOES

What eth_signTypedData_v4 does on Privy MCP Server

AI agents invoke eth_signTypedData_v4 to trigger actions in Privy MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why eth_signTypedData_v4 needs a policy

Signing typed data (EIP-712) is a cryptographic operation that produces a valid signature which can authorize off-chain or on-chain actions (e.g., permit approvals, meta-transactions, order placements on DEXs). While it doesn't directly broadcast a transaction, the resulting signature can be used to authorize financial operations or smart contract interactions.

From the tool's definition Sign EIP-712 typed data using eth_signTypedData_v4 method

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

eth_signTypedData_v4 Rate-limited

eth_signTypedData_v4 stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "eth_signTypedData_v4": {
      "limits": [
        {
          "counter": "eth_signtypeddata_v4_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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_signTypedData_v4

What does the eth_signTypedData_v4 tool do? +

Sign EIP-712 typed data using eth_signTypedData_v4 method. It is categorised as a Execute tool in the Privy MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on eth_signTypedData_v4? +

Register the Privy MCP Server MCP server in PolicyLayer and add a rule for eth_signTypedData_v4: 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_signTypedData_v4? +

eth_signTypedData_v4 is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit eth_signTypedData_v4? +

Yes. Add a rate_limit block to the eth_signTypedData_v4 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_signTypedData_v4 completely? +

Set action: deny in the PolicyLayer policy for eth_signTypedData_v4. 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_signTypedData_v4? +

eth_signTypedData_v4 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.