ows_sign_eip191 · Execution Market MCP: Risk & Policy

WHAT IT DOES

What ows_sign_eip191 does on Execution Market

AI agents invoke ows_sign_eip191 to trigger actions in Execution Market. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why ows_sign_eip191 needs a policy

Cryptographic signing of Ethereum messages is an Execute-level action with significant security implications. While it doesn't directly move funds, EIP-191 signed messages can be used to authorize transactions, prove identity, approve contract interactions, or unlock financial operations on-chain.

From the tool's definition Sign a message with EIP-191 prefix (\x19Ethereum Signed Message)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

ows_sign_eip191 Rate-limited

ows_sign_eip191 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "ows_sign_eip191": {
      "limits": [
        {
          "counter": "ows_sign_eip191_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about ows_sign_eip191

What does the ows_sign_eip191 tool do? +

Sign a message with EIP-191 prefix (\\x19Ethereum Signed Message). It is categorised as a Execute tool in the Execution Market MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on ows_sign_eip191? +

Register the Execution Market MCP server in PolicyLayer and add a rule for ows_sign_eip191: 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 Execution Market. Nothing to install.

What risk level is ows_sign_eip191? +

ows_sign_eip191 is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit ows_sign_eip191? +

Yes. Add a rate_limit block to the ows_sign_eip191 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 ows_sign_eip191 completely? +

Set action: deny in the PolicyLayer policy for ows_sign_eip191. 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 ows_sign_eip191? +

ows_sign_eip191 is provided by the Execution Market MCP server (https://mcp.execution.market/mcp/). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.