Lists all Vapi phone numbers
AI agents call list_phone_numbers to retrieve information from Vapi 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 and displays existing phone numbers without creating, modifying, deleting, or executing any external operations. It is a read-only query operation with minimal blast radius if misused by an AI agent—the worst outcome would be unauthorized enumeration of phone numbers, which is a confidentiality concern but not operationally destructive.
From the tool's definition Tool name 'list_phone_numbers' and description 'Lists all Vapi phone numbers' indicate a query/retrieval operation with no modifications or side effects.
Attacks that exploit this kind of access
Lists all Vapi phone numbers. It is categorised as a Read tool in the Vapi MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Vapi MCP Server MCP server in PolicyLayer and add a rule for list_phone_numbers: 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 Vapi MCP Server. Nothing to install.
list_phone_numbers 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_phone_numbers 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_phone_numbers. 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_phone_numbers is provided by the Vapi MCP Server MCP server (kuchikirenji/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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