AI agents invoke sign_message to trigger actions in Waiaas. 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.
The description is empty, lowering confidence. However, in the context of a self-hosted wallet MCP server for AI agents handling crypto operations, 'sign_message' likely cryptographically signs a message or transaction using a private key. Signing can authorize transactions, approvals, or other on-chain operations, making it an Execute-level action.
From the tool's definition Tool name 'sign_message' on a crypto wallet MCP server that provides multi-chain crypto operations including transfers, DeFi, and payments.
Documented attack patterns abuse exactly the kind of access sign_message gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Waiaas, and nothing reaches the server without passing your rules. This is the rule we recommend for sign_message:
{
"version": "1",
"default": "deny",
"tools": {
"sign_message": {
"limits": [
{
"counter": "sign_message_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}sign_message 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.
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sign_message. It is categorised as a Execute tool in the Waiaas MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Waiaas MCP server in PolicyLayer and add a rule for sign_message: 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 Waiaas. Nothing to install.
sign_message 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 sign_message 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 sign_message. 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.
sign_message is provided by the Waiaas MCP server (minhoyoo-iotrust/waiaas). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Waiaas, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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126 Waiaas tools catalogued and risk-classified — across an index of 43,000+ MCP servers.