AI agents invoke hangup_call to trigger actions in Voyp MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
Hanging up a call is an external operation that terminates an ongoing telephony session. It is not purely destructive (no data is deleted), not financial, and not a simple read/write — it executes an action against an external system (the live call). Misuse could disrupt legitimate calls, giving it medium severity.
From the tool's definition 'Hangup an existing call' — terminates an active telephony session, an external real-world operation with immediate effect on a live call
Documented attack patterns abuse exactly the kind of access hangup_call gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Voyp MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for hangup_call:
{
"version": "1",
"default": "deny",
"tools": {
"hangup_call": {
"limits": [
{
"counter": "hangup_call_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}hangup_call stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Hangup an existing call. It is categorised as a Execute tool in the Voyp MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Voyp MCP Server MCP server in PolicyLayer and add a rule for hangup_call: 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 Voyp MCP Server. Nothing to install.
hangup_call is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the hangup_call 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 hangup_call. 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.
hangup_call is provided by the Voyp MCP Server MCP server (paulotaylor/voyp-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Voyp MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
7 Voyp MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.