AI agents call get-token-balance to retrieve information from MetaMask MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries blockchain state to retrieve balance information for a given address. It has no side effects, does not modify data, and does not execute transactions or commands. It is a straightforward read-only operation, placing it in the Read category with low severity.
From the tool's definition Tool name 'get-token-balance' and description 'Get token balance of an address' indicate a query operation that retrieves data without modifying state or executing transactions.
Documented attack patterns abuse exactly the kind of access get-token-balance 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 get-token-balance:
{
"version": "1",
"default": "deny",
"tools": {
"get-token-balance": {}
}
}get-token-balance is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get token balance of an address. It is categorised as a Read tool in the MetaMask MCP MCP Server, which means it retrieves data without modifying state.
Register the MetaMask MCP server in PolicyLayer and add a rule for get-token-balance: 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.
get-token-balance is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get-token-balance 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 get-token-balance. 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.
get-token-balance 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.
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29 MetaMask MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.