Executing a new message call immediately without submitting a transaction to the network.
AI agents invoke call to trigger actions in MetaMask MCP. 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 tool executes a message call on the blockchain (e.g., calling a smart contract function). While it doesn't submit a transaction and thus has no on-chain state changes, it still executes arbitrary code/calls against the network. It falls under Execute because it runs an operation whose effects depend on the arguments passed.
From the tool's definition Executing a new message call immediately without submitting a transaction to the network.
Documented attack patterns abuse exactly the kind of access call gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MetaMask MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for call:
{
"version": "1",
"default": "deny",
"tools": {
"call": {
"limits": [
{
"counter": "call_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}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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Executing a new message call immediately without submitting a transaction to the network. It is categorised as a Execute tool in the MetaMask MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the MetaMask MCP server in PolicyLayer and add a rule for 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 MetaMask MCP. Nothing to install.
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 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 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.
call is provided by the MetaMask MCP server (xiawpohr/metamask-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MetaMask MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
29 MetaMask MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.