retell_update_call · Retell AI MCP Server MCP: Risk & Policy

WHAT IT DOES

What retell_update_call does on Retell AI MCP Server

AI agents use retell_update_call to create or update resources in Retell AI MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Retell AI MCP Server environment.

WHY IT NEEDS A POLICY

Why retell_update_call needs a policy

This tool modifies call metadata and data storage settings reversibly without deleting data or executing arbitrary operations. It represents a Write operation—creating or modifying data that could be changed back.

From the tool's definition Tool name 'retell_update_call' and description 'Update call metadata or data storage settings for a specific call' indicate modification of existing call data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

retell_update_call Rate-limited

retell_update_call stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "retell_update_call": {
      "limits": [
        {
          "counter": "retell_update_call_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about retell_update_call

What does the retell_update_call tool do? +

Update call metadata or data storage settings for a specific call. It is categorised as a Write tool in the Retell AI MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on retell_update_call? +

Register the Retell AI MCP Server MCP server in PolicyLayer and add a rule for retell_update_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 Retell AI MCP Server. Nothing to install.

What risk level is retell_update_call? +

retell_update_call is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit retell_update_call? +

Yes. Add a rate_limit block to the retell_update_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 retell_update_call completely? +

Set action: deny in the PolicyLayer policy for retell_update_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 retell_update_call? +

retell_update_call is provided by the Retell AI MCP Server MCP server (itsanamune/retellsimp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.