contract__getsourcecode

THE RISK

Low Risk

Why contract__getsourcecode needs a policy

This is a data retrieval operation that queries publicly available blockchain information (verified contract source codes). It has no side effects, does not execute code, does not modify data, and does not move funds. The worst-case misuse would be collecting public code for analysis, which poses minimal risk. Classification: Read with low severity.

From the tool's definition Tool returns contract source code data via query; description states 'Returns the Contract Source Code' with no mention of modification, execution, or side effects. Verified contracts are public information on the blockchain.

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

POLICY

How to control contract__getsourcecode

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 contract__getsourcecode:

policy.json

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

contract__getsourcecode 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.

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EXPLORE

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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 contract__getsourcecode

What does the contract__getsourcecode tool do? +

Returns the Contract Source Code for Verified Contract Source Codes. 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 contract__getsourcecode? +

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

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

Can I rate-limit contract__getsourcecode? +

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

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

contract__getsourcecode 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 →