# Retell AI

Wires Retell AI voice agents into your assistant: place a call, read call history, edit an agent prompt.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI · ★ 13
- Author: mindstone
- License: not stated · policy=link-only · description only; the file stays with the author
- Source: https://github.com/mindstone/mcp-servers/tree/HEAD/connectors/retell-ai
- Updated: 2026-10-22
- HTML: https://affpapa.org/en/nevibecode/mcp/retell-ai

## What it does

Retell AI is a local stdio MCP server that exposes Retell AI phone operations to your assistant. It ships 32 tools covering calls, agents, LLM prompts, voices, knowledge bases and chat history. A typical run inspects the agent and its prompt, picks a number, then dials.

Outbound calling is a real-world action. The host has to show you `from_number` and `to_number` and wait for your confirmation before every `create_phone_call`. Prior approvals do not carry over — each call gets confirmed on its own. Numbers are checked locally against E.164, so a malformed one comes back as `INVALID_PHONE_NUMBER` and never reaches Retell. Billing runs per minute on your Retell AI plan, which makes a stray call an actual expense.

\`create_batch_call` fires one billed call per task, and the confirmation rules are the same: surface the whole recipient list first. Check `get_concurrency` before a campaign, or it can crowd out inbound capacity. Knowledge-base uploads read only inside `MCP_WORKSPACE_PATH`, falling back to the system temp directory when that is unset; `..` traversal and escaping symlinks are refused before any disk read. You need Node.js 20+, npm and a `RETELL_API_KEY`.

## Requirements
- Needs: Node.js (commands run via npx)
- Environment variables: `RETELL_API_KEY`, `MCP_WORKSPACE_PATH` — keys and tokens: ask the human for the values, never commit them or put them in shared files.

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add --env RETELL_API_KEY=<RETELL_API_KEY> --env MCP_WORKSPACE_PATH=<MCP_WORKSPACE_PATH> --transport stdio retell-ai -- npx -y @mindstone/mcp-server-retell-ai
```
Replace <…> with your own values

### Codex

**Platform CLI**
```bash
codex mcp add retell-ai --env RETELL_API_KEY=<RETELL_API_KEY> --env MCP_WORKSPACE_PATH=<MCP_WORKSPACE_PATH> -- npx -y @mindstone/mcp-server-retell-ai
```
Replace <…> with your own values

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "retell-ai": {
            "command": "npx",
            "args": [
                "-y",
                "@mindstone/mcp-server-retell-ai"
            ],
            "env": {
                "RETELL_API_KEY": "<RETELL_API_KEY>",
                "MCP_WORKSPACE_PATH": "<MCP_WORKSPACE_PATH>"
            }
        }
    }
}
```
Replace <…> with your own values

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "retell-ai": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "@mindstone/mcp-server-retell-ai"
            ],
            "env": {
                "RETELL_API_KEY": "<RETELL_API_KEY>",
                "MCP_WORKSPACE_PATH": "<MCP_WORKSPACE_PATH>"
            }
        }
    }
}
```
Replace <…> with your own values

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add -e RETELL_API_KEY=<RETELL_API_KEY> -e MCP_WORKSPACE_PATH=<MCP_WORKSPACE_PATH> retell-ai npx -y @mindstone/mcp-server-retell-ai
```
Replace <…> with your own values

## When to use it
- call a customer with a voice agent and keep the recording
- pull the transcript and status of a finished call
- edit an agent prompt before a campaign goes out
- check free capacity ahead of a batch dialer run
- upload documents into an agent knowledge base

## Example prompts
- Call Jane with the support agent and confirm tomorrow's appointment
- Show me the status and transcript of the last call
- Check the support agent's prompt and its dynamic variables

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From the same set: [mindstone/mcp-servers](https://affpapa.org/en/nevibecode/by/mindstone/mcp-servers.md) — 13 cards

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