eth_send_transaction · Portal MCP: Risk & Policy

WHAT IT DOES

What eth_send_transaction does on PortalMCP

AI agents use eth_send_transaction to create or update resources in PortalMCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your PortalMCP environment.

WHY IT NEEDS A POLICY

Why eth_send_transaction needs a policy

An AI agent can call eth_send_transaction faster than any human can review — one bad instruction and it creates or modifies resources in PortalMCP by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

eth_send_transaction Rate-limited

eth_send_transaction stays usable, but capped — an agent stuck in a loop can't make hundreds of changes 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_send_transaction": {
      "limits": [
        {
          "counter": "eth_send_transaction_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about eth_send_transaction

What does the eth_send_transaction tool do? +

Prepare a generic transaction to be signed by the user\. It is categorised as a Write tool in the PortalMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on eth_send_transaction? +

Register the Portal MCP server in PolicyLayer and add a rule for eth_send_transaction: 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 PortalMCP. Nothing to install.

What risk level is eth_send_transaction? +

eth_send_transaction is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit eth_send_transaction? +

Yes. Add a rate_limit block to the eth_send_transaction 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_send_transaction completely? +

Set action: deny in the PolicyLayer policy for eth_send_transaction. 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_send_transaction? +

eth_send_transaction is provided by the Portal MCP server (portalfnd/portalmcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.