voice_call

Initiate an outbound phone call via ElevenLabs Agents + Twilio integration.

SERVERCoWork OS SOURCECoWork-OS/CoWork-OS

High RISK CLASS

Category Execute

Parameters 00 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/cowork-os/voice-call.md

WHAT IT DOES

What voice_call does on CoWork OS

AI agents invoke voice_call to trigger actions in CoWork OS. 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.

RISK

Why voice_call is rated High

This tool triggers an external real-world operation (an outbound phone call) using third-party services (ElevenLabs + Twilio). It is not merely reading or writing data — it executes an action with real-world side effects (calling a phone number). Misuse could result in harassment, unwanted calls, or social engineering attacks, making severity high.

From the tool's definition Initiate an outbound phone call via ElevenLabs Agents + Twilio integration

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs voice_call safely

PolicyLayer is an MCP gateway: it sits between your AI agents and CoWork OS, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For voice_call, this is the rule to start with:

voice_call Rate-limited

voice_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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "voice_call": {
      "limits": [
        {
          "counter": "voice_call_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect CoWork OS, apply this rule, and every voice_call call is checked against it from then on.

FAQ

Questions about voice_call

What does the voice_call tool do? +

Initiate an outbound phone call via ElevenLabs Agents + Twilio integration. It is categorised as a Execute tool in the CoWork OS MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on voice_call? +

Register the CoWork OS MCP server in PolicyLayer and add a rule for voice_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 CoWork OS. Nothing to install.

What risk level is voice_call? +

voice_call is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit voice_call? +

Yes. Add a rate_limit block to the voice_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.

How do I block voice_call completely? +

Set action: deny in the PolicyLayer policy for voice_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.

What MCP server provides voice_call? +

voice_call is provided by the CoWork OS MCP server (CoWork-OS/CoWork-OS). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

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