Parameters: - method (string, REQUIRED): The JSON-RPC method to execute. - params (array, REQUIRED): The parameters for the JSON-RPC method.
AI agents invoke eth_json_rpc_call to trigger actions in Ethereum RPC MPC Server. 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.
This tool provides unrestricted access to the full Ethereum JSON-RPC API surface. While it includes read operations (eth_getBalance, eth_blockNumber), the capability to execute arbitrary methods means an AI agent can invoke state-changing calls that transfer funds, approve token transfers, execute arbitrary smart contract functions, or trigger external operations.
From the tool's definition Accepts arbitrary JSON-RPC methods with unrestricted parameters ('method (string, REQUIRED): The JSON-RPC method to execute' and 'params (array, REQUIRED): The parameters for the JSON-RPC method').
Documented attack patterns abuse exactly the kind of access eth_json_rpc_call gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Ethereum RPC MPC Server, and nothing reaches the server without passing your rules. This is the rule we recommend for eth_json_rpc_call:
{
"version": "1",
"default": "deny",
"tools": {
"eth_json_rpc_call": {
"limits": [
{
"counter": "eth_json_rpc_call_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}eth_json_rpc_call 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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Parameters: - method (string, REQUIRED): The JSON-RPC method to execute. - params (array, REQUIRED): The parameters for the JSON-RPC method. It is categorised as a Execute tool in the Ethereum RPC MPC Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Ethereum RPC MPC Server MCP server in PolicyLayer and add a rule for eth_json_rpc_call: 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 Ethereum RPC MPC Server. Nothing to install.
eth_json_rpc_call 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 eth_json_rpc_call 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 eth_json_rpc_call. 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.
eth_json_rpc_call is provided by the Ethereum RPC MPC Server MCP server (kemperino/ethereum-rpc-mpc). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Ethereum RPC MPC Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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3 Ethereum RPC MPC Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.