AI agents invoke build_userop 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.
Although the description is empty, the tool name and server context make clear this builds UserOperations for blockchain execution. The blast radius is critical: a misused build_userop could construct operations that drain wallets, manipulate DeFi protocols, or transfer assets.
From the tool's definition Tool name 'build_userop' indicates construction of a UserOperation (a key EVM account abstraction mechanism).
Documented attack patterns abuse exactly the kind of access build_userop 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 build_userop:
{
"version": "1",
"default": "deny",
"tools": {
"build_userop": {
"limits": [
{
"counter": "build_userop_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}build_userop 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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build_userop. 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 build_userop: 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.
build_userop 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 build_userop 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 build_userop. 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.
build_userop 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.