AI agents call get_token_balances to retrieve information from Zapper without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs read-only data retrieval of cryptocurrency token balances from a wallet. It has no side effects, cannot modify data, execute commands, or affect financial transactions. It simply queries and returns balance information, fitting squarely in the Read category. Severity is low because unauthorized access reveals financial information but does not enable direct funds transfer or irreversible actions.
From the tool's definition Tool description explicitly states it retrieves 'token balances' and is used 'when the question is specifically about token holdings' — purely a query operation with no modification, deletion, or execution of code.
Attacks that exploit this kind of access
Spot token balances only (no DeFi positions). Use when the question is specifically about token holdings:. It is categorised as a Read tool in the Zapper MCP Server, which means it retrieves data without modifying state.
Register the Zapper MCP server in PolicyLayer and add a rule for get_token_balances: 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 Zapper. Nothing to install.
get_token_balances 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_balances 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_balances. 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_balances is provided by the Zapper MCP server (mehdi-loup/zapper-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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