proxy__eth_estimateGas

THE RISK

High Risk

Why proxy__eth_estimateGas needs a policy

eth_estimateGas triggers a simulation of a transaction execution on the blockchain node. While it doesn't submit a real transaction, it runs code/transaction logic and has external operation side effects. The description is truncated ('which won') reducing confidence slightly, but the standard Ethereum eth_estimateGas behavior is well-known as a simulated execution call.

From the tool's definition 'eth_estimateGas' — executes a simulated call or transaction on the Ethereum network to estimate gas costs

Documented attack patterns abuse exactly the kind of access proxy__eth_estimateGas gives an agent:

POLICY

How to control proxy__eth_estimateGas

PolicyLayer is an MCP gateway — it sits between your AI agents and Etherscan MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for proxy__eth_estimateGas:

policy.json

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

proxy__eth_estimateGas 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.

Create a free account and register Etherscan MCP — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

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EXPLORE

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Go deeper

High-risk tools in Etherscan MCP → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about proxy__eth_estimateGas

What does the proxy__eth_estimateGas tool do? +

Makes a call or transaction, which won. It is categorised as a Execute tool in the Etherscan MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on proxy__eth_estimateGas? +

Register the Etherscan MCP server in PolicyLayer and add a rule for proxy__eth_estimateGas: 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 Etherscan MCP. Nothing to install.

What risk level is proxy__eth_estimateGas? +

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

Can I rate-limit proxy__eth_estimateGas? +

Yes. Add a rate_limit block to the proxy__eth_estimateGas 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 proxy__eth_estimateGas completely? +

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

proxy__eth_estimateGas is provided by the Etherscan MCP server (xiaok/etherscan-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Etherscan MCP tool call.

Start from Etherscan MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

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