AI agents call list_cards to retrieve information from Z Zero without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and displays card aliases and balance information without creating, modifying, or deleting data. It has no side effects and poses minimal risk even if called repeatedly or with unexpected arguments. The explicit note that no sensitive data is returned further reduces the risk profile to low severity.
From the tool's definition Tool name 'list_cards' and description 'List all available virtual card aliases and their balances' indicates a query operation that retrieves information without modification.
Attacks that exploit this kind of access
List all available virtual card aliases and their balances. No sensitive data is returned. It is categorised as a Read tool in the Z Zero MCP Server, which means it retrieves data without modifying state.
Register the Z Zero MCP server in PolicyLayer and add a rule for list_cards: 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 Z Zero. Nothing to install.
list_cards 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 list_cards 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 list_cards. 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.
list_cards is provided by the Z Zero MCP server (z-zero-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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