proxy__eth_getBlockByNumber

THE RISK

Low Risk

Why proxy__eth_getBlockByNumber needs a policy

This tool queries and retrieves block data from the Ethereum blockchain. It performs a read-only operation (get/fetch) without creating, modifying, deleting, or executing any code. While blockchain data could be used by an AI agent for various purposes, the tool itself only exposes information retrieval with no destructive, financial, or code execution capabilities.

From the tool's definition Tool name 'eth_getBlockByNumber' and description 'Returns information about a block by block number' indicate a pure data retrieval operation with no side effects or state modifications.

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

POLICY

How to control proxy__eth_getBlockByNumber

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_getBlockByNumber:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "proxy__eth_getBlockByNumber": {}
  }
}

proxy__eth_getBlockByNumber is read-only, so it stays allowed — but 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.

CAP THIS TOOL →

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EXPLORE

Related tools and policies

More Etherscan MCP tools

Execute proxy__eth_call Executes a new message call immediately without creating a transaction on the block chain. Execute proxy__eth_estimateGas Makes a call or transaction, which won Read account__balance Returns the Ether balance of a given address. Read account__balancemulti Get Ether Balance for Multiple Addresses in a Single Call Read account__fundedby Returns the address that funded an address, and its relative age. Read account__getminedblocks Returns the list of blocks validated by an address. Read account__token1155tx Returns the list of ERC1155 Token Transfer Events by Address Read account__tokenbalance Returns the current balance of an ERC-20 token of an address.

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about proxy__eth_getBlockByNumber

What does the proxy__eth_getBlockByNumber tool do? +

Returns information about a block by block number. It is categorised as a Read tool in the Etherscan MCP MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on proxy__eth_getBlockByNumber? +

Register the Etherscan MCP server in PolicyLayer and add a rule for proxy__eth_getBlockByNumber: 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_getBlockByNumber? +

proxy__eth_getBlockByNumber is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit proxy__eth_getBlockByNumber? +

Yes. Add a rate_limit block to the proxy__eth_getBlockByNumber 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_getBlockByNumber completely? +

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

proxy__eth_getBlockByNumber 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.

CHECK YOUR STACK →