Check wallet balances. For Sonic: native S token and common ERC20 tokens (wS, WETH, USDC). For Ethereum: native ETH only. If address is not provided, uses WALLET_ADDRESS from environment.
AI agents call check_balance to retrieve information from Sonic Blockchain MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves blockchain balance data without side effects. While it accesses financial information, it does not move money, execute code, or modify data. It is purely informational (Read category). The severity is low because balance queries have no blast radius—they cannot cause harm even if misused, as they only return current state information.
From the tool's definition Tool description states it 'Check wallet balances' and retrieves token information. The name and description indicate read-only operations that query balances without modifying state or triggering financial transactions.
Attacks that exploit this kind of access
Check wallet balances. For Sonic: native S token and common ERC20 tokens (wS, WETH, USDC). For Ethereum: native ETH only. If address is not provided, uses WALLET_ADDRESS from environment. It is categorised as a Read tool in the Sonic Blockchain MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Sonic Blockchain MCP Server MCP server in PolicyLayer and add a rule for check_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 Sonic Blockchain MCP Server. Nothing to install.
check_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 check_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 check_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.
check_balance is provided by the Sonic Blockchain MCP Server MCP server (tairon-ai/sonic-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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