web3_challenge

THE RISK

Low Risk

Why web3_challenge needs a policy

This tool performs a read operation by generating and returning a SIWE challenge message for authentication purposes. There are no side effects, data modifications, code execution, financial transactions, or destructive operations.

From the tool's definition Get a SIWE (Sign-In with Ethereum) challenge message for a wallet address. The tool retrieves a challenge message; it does not modify data, execute code, delete anything, or move funds.

Documented attack patterns abuse exactly the kind of access web3_challenge gives an agent:

POLICY

How to control web3_challenge

PolicyLayer is an MCP gateway — it sits between your AI agents and 0xarchive, and nothing reaches the server without passing your rules. This is the rule we recommend for web3_challenge:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "web3_challenge": {}
  }
}

web3_challenge 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 0xarchive — 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 →

Free to start. No card required.

EXPLORE

Related tools and policies

More 0xarchive tools

Financial web3_subscribe Subscribe to a paid tier (build or pro) using x402 USDC payment on Base.\n\n Destructive web3_revoke_key Revoke a specific API key. Requires a fresh SIWE challenge signed with personal_sign. Write web3_signup Create a free-tier 0xArchive account and get an API key using a signed SIWE message. Read web3_list_keys List all API keys for a wallet. Requires a fresh SIWE challenge signed with personal_sign.

All 5 0xarchive tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history EMBA-MCP explain_attack_path

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 web3_challenge

What does the web3_challenge tool do? +

Get a SIWE (Sign-In with Ethereum) challenge message for a wallet address. It is categorised as a Read tool in the 0xarchive MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on web3_challenge? +

Register the 0xarchive MCP server in PolicyLayer and add a rule for web3_challenge: 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 0xarchive. Nothing to install.

What risk level is web3_challenge? +

web3_challenge is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit web3_challenge? +

Yes. Add a rate_limit block to the web3_challenge 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 web3_challenge completely? +

Set action: deny in the PolicyLayer policy for web3_challenge. 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 web3_challenge? +

web3_challenge is provided by the 0xarchive MCP server (0xarchiveio/0xarchive-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every 0xarchive tool call.

Start from 0xarchive, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →