Check account balance, lifetime top-up amount, and current volume pricing tier.
AI agents call check_balance to retrieve information from Postcardbot without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool only queries and retrieves financial account data (balance, top-up history, pricing tier). It performs no writes, modifications, deletions, or financial transactions. The 'check' verb and read-only nature of retrieving account status information places it firmly in the Read category.
From the tool's definition Tool description states 'Check account balance, lifetime top-up amount, and current volume pricing tier' — purely retrieves account information with no modification or side effects.
Attacks that exploit this kind of access
Check account balance, lifetime top-up amount, and current volume pricing tier. It is categorised as a Read tool in the Postcardbot MCP Server, which means it retrieves data without modifying state.
Register the Postcardbot 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 Postcardbot. 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 Postcardbot MCP server (postcardbot/mcp-server). 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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