// MCP TOOL REFERENCE

create_call

Initiate a voice call via Twilio

Incurs per-minute call charges

Part of the Twilio MCP server. Enforce policies on this tool with Intercept, the open-source MCP proxy.

// WHEN AI AGENTS USE THIS TOOL

AI agents use create_call to initiate financial transactions through Twilio. Financial operations involve real money and are irreversible once processed. Intercept blocks financial tools by default, requiring explicit human approval with transaction-level limits to prevent unauthorised spending.

// WHY ENFORCE A POLICY ON CREATE_CALL

create_call moves real money. Without a policy, an autonomous agent could initiate transactions that drain accounts or exceed budgets. Intercept blocks financial tools by default, requiring human-in-the-loop approval with configurable spending limits per transaction and per time window.

// RECOMMENDED POLICY

Financial tools involve real money. Block by default and require explicit human approval before enabling.

twilio.yaml

tools:
  create_call:
    rules:
      - action: deny
        reason: "Requires human approval"

See the full Twilio policy for all 36 tools.

// DETAILS

Tool Name create_call

Category Financial

MCP Server Twilio MCP Server

Risk Level Critical

// MORE TWILIO TOOLS

Financial create_incoming_phone_number Financial create_verification Financial send_message Execute create_deployment Execute create_execution Write add_conversation_participant Write create_conversation Write create_function

View all 36 tools →

// WHAT CAN GO WRONG

Agents calling financial-class tools like create_call have been implicated in these attack patterns. Read the full case and prevention policy for each:

Browse the full MCP Attack Database →

// OTHER FINANCIAL TOOLS ACROSS MCP SERVERS

Other tools in the Financial risk category across the catalogue. The same policy patterns (deny, require_approval) apply to each.

Atv build_deposit_tx Atv build_queue_withdraw_tx Atv build_redeem_withdraw_tx Atv build_unqueue_withdraw_tx Atv build_withdraw_tx AbraFlexi bank_transaction_create

// IN CONTEXT OF CRITICAL RISK

create_call is one of the critical-risk operations in Twilio. For the full severity-focused view — only the critical-risk tools with their recommended policies — see the breakdown for this server, or browse all critical-risk tools across every MCP server.

// RELATED READING

// FAQ

What does the create_call tool do? +

Initiate a voice call via Twilio. It is categorised as a Financial tool in the Twilio MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on create_call? +

Add a rule in your Intercept YAML policy under the tools section for create_call. You can allow, deny, rate-limit, or validate arguments. Then run Intercept as a proxy in front of the Twilio MCP server.

What risk level is create_call? +

create_call is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit create_call? +

Yes. Add a rate_limit block to the create_call rule in your Intercept 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 create_call completely? +

Set action: deny in the Intercept policy for create_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 create_call? +

create_call is provided by the Twilio MCP server (@twilio-labs/mcp). Intercept sits as a proxy in front of this server to enforce policies before tool calls reach the server.

create_call

Let agents act without letting them run wild.