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Retell AI MCP Integration for LangGraph

Connect Retell AI to LangGraph through the local KosmoKrator MCP gateway with scoped tools, credentials, and write policy.

7 functions 5 read 2 write Bearer token auth
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Connect Retell AI to LangGraph

Run KosmoKrator integration calls from LangGraph nodes while preserving local credentials and permissions.

Use a graph node that calls the KosmoKrator CLI for deterministic steps or an MCP client for dynamic tool selection. The gateway is local, scoped to this integration, and starts with --write=deny so LangGraph can inspect read-capable tools without receiving write access by default.

Retell AI MCP Config for LangGraph

Headless CLI calls fit repeatable graph edges; MCP fits exploratory agent nodes.

{
  "mcpServers": {
    "kosmokrator-retell": {
      "type": "stdio",
      "command": "kosmo",
      "args": [
        "mcp:serve",
        "--integration=retell",
        "--write=deny"
      ]
    }
  }
}

Run the Gateway Manually

kosmokrator mcp:serve --integration=retell --write=deny

Why Use KosmoKrator Here

Scoped tools

Expose only Retell AI instead of a broad multi-service tool list.

Local credentials

Reuse credentials already configured for the KosmoKrator CLI and Lua runtime.

Write policy

Start read-only, then opt into ask or allow for trusted workspaces.

Retell AI Tools Visible to LangGraph

LangGraph sees stable MCP tool names generated from the Retell AI integration catalog.

MCP toolSource functionTypeDescription
integration__retell__retell_list_calls retell.retell_list_calls Read List AI voice calls from Retell. Supports filtering by criteria and cursor-based pagination using before/after timestamps.
integration__retell__retell_get_call retell.retell_get_call Read Get detailed information about a specific AI voice call, including transcript, duration, and status.
integration__retell__retell_create_phone_call retell.retell_create_phone_call Write Create a new AI-powered phone call using a Retell AI agent. The agent will handle the conversation automatically.
integration__retell__retell_list_agents retell.retell_list_agents Read List all AI voice agents configured in Retell AI. Returns agent IDs, names, and configuration details.
integration__retell__retell_get_agent retell.retell_get_agent Read Get detailed information about a specific AI voice agent, including its model, voice, prompt, and configuration.
integration__retell__retell_create_agent retell.retell_create_agent Write Create a new AI voice agent in Retell AI. Configure the model, voice, system prompt, and response engine.
integration__retell__retell_get_current_user retell.retell_get_current_user Read Get information about the currently authenticated Retell AI user. Useful for verifying credentials and account details.

Related Retell AI Pages

Retell AI CLIUse direct JSON commands instead of MCP discovery. Retell AI MCPFull gateway reference and MCP tool names. KosmoKrator for LangGraphClient-level gateway setup.