Get token balances for a wallet address
AI agents call get_account_balance to retrieve information from Web3 without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves blockchain data without side effects. It queries and returns token balance information for a specified wallet address. No data is created, modified, deleted, or executed. The blast radius of misuse is minimal—an attacker could enumerate wallet balances but cannot move funds, execute transactions, or alter state. Classified as Read with low severity and high confidence.
From the tool's definition Tool name and description indicate data retrieval: 'Get token balances for a wallet address' with no modification, deletion, or execution capability.
Documented attack patterns abuse exactly the kind of access get_account_balance gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Web3, and nothing reaches the server without passing your rules. This is the rule we recommend for get_account_balance:
{
"version": "1",
"default": "deny",
"tools": {
"get_account_balance": {}
}
}get_account_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 balances for a wallet address. It is categorised as a Read tool in the Web3 MCP Server, which means it retrieves data without modifying state.
Register the Web3 MCP server in PolicyLayer and add a rule for get_account_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 Web3. Nothing to install.
get_account_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_account_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_account_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_account_balance is provided by the Web3 MCP server (tumf/web3-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Web3, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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17 Web3 tools catalogued and risk-classified — across an index of 43,000+ MCP servers.