ows_sign_eip191
Sign a message with EIP-191 prefix (\\x19Ethereum Signed Message).
This record as markdown: /tools/market-execution-execution-market/ows-sign-eip191.md
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 ows_sign_eip191 is rated High
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
The rule that runs ows_sign_eip191 safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Execution Market, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For ows_sign_eip191, this is the rule to start with:
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.
The button opens the PolicyLayer dashboard: create your workspace, connect Execution Market, apply this rule, and every ows_sign_eip191 call is checked against it from then on.
Questions about ows_sign_eip191
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.
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.
ows_sign_eip191 is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
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.
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.
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.
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