AI agents call getBalance to retrieve information from Web3 MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs a read-only operation on the blockchain. It queries and returns balance information for a specified address with no side effects, no state changes, and no ability to transfer funds or execute transactions. While the Web3 server contains financial tools (executeSwap, approveEvmToken), this specific tool is purely informational.
From the tool's definition Tool name 'getBalance' and description 'Get balance for a Solana address' indicate a query operation that retrieves account balance information without modifying any blockchain state.
Documented attack patterns abuse exactly the kind of access getBalance gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Web3 MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for getBalance:
{
"version": "1",
"default": "deny",
"tools": {
"getBalance": {}
}
}getBalance is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Get balance for a Solana address. It is categorised as a Read tool in the Web3 MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Web3 MCP Server MCP server in PolicyLayer and add a rule for getBalance: 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 MCP Server. Nothing to install.
getBalance 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 getBalance 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 getBalance. 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.
getBalance is provided by the Web3 MCP Server MCP server (strangelove-ventures/web3-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 55 Web3 MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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55 Web3 MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.