AI agents call vapi_list_calls to retrieve information from Mcp Vapi without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and retrieves call history data without side effects. It performs a simple list/read operation with optional filters, characteristic of a Read category tool. The low severity reflects that retrieving call metadata poses minimal risk even if misused by an agent, though the cost field could inform financial decisions (but the tool itself does not move money).
From the tool's definition Tool description states it 'List calls' and 'Returns call IDs, status, cost, and basic info' — purely retrieval operations with no modification, deletion, or execution of external actions.
Attacks that exploit this kind of access
List calls with optional filters. Returns call IDs, status, cost, and basic info. It is categorised as a Read tool in the Mcp Vapi MCP Server, which means it retrieves data without modifying state.
Register the Mcp Vapi MCP server in PolicyLayer and add a rule for vapi_list_calls: 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 Mcp Vapi. Nothing to install.
vapi_list_calls 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 vapi_list_calls 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 vapi_list_calls. 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.
vapi_list_calls is provided by the Mcp Vapi MCP server (adhirajhangal/mcp-vapi). 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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