twilio_send_sms · VibeServe MCP: Risk & Policy

WHAT IT DOES

What twilio_send_sms does on VibeServe

AI agents invoke twilio_send_sms to trigger actions in VibeServe. 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.

WHY IT NEEDS A POLICY

Why twilio_send_sms needs a policy

Sending an SMS is an external operation that cannot be undone once dispatched. It may incur costs (Twilio charges per message), could be used to spam or phish recipients, and involves communicating with external parties. While it has a financial dimension, it is not a direct financial transaction but rather an external API execution with potential for abuse at scale.

From the tool's definition 'Send an SMS via Twilio' — triggers an external operation (SMS delivery) through the Twilio API with real-world side effects

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

twilio_send_sms Rate-limited

twilio_send_sms 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": {
    "twilio_send_sms": {
      "limits": [
        {
          "counter": "twilio_send_sms_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches VibeServe, so you can run agents against it safely.

FAQ

Questions about twilio_send_sms

What does the twilio_send_sms tool do? +

Send an SMS via Twilio. It is categorised as a Execute tool in the VibeServe MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on twilio_send_sms? +

Register the VibeServe MCP server in PolicyLayer and add a rule for twilio_send_sms: 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 VibeServe. Nothing to install.

What risk level is twilio_send_sms? +

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

Can I rate-limit twilio_send_sms? +

Yes. Add a rate_limit block to the twilio_send_sms 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 twilio_send_sms completely? +

Set action: deny in the PolicyLayer policy for twilio_send_sms. 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 twilio_send_sms? +

twilio_send_sms is provided by the VibeServe MCP server (ncsound919/vibeserve). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.