Retell AI MCP Server

Instructions

Implementation Reference

• src/index.ts:1215-1216 (handler)

  Handler case in the executeTool function that proxies the tool call to Retell's /create-conversation-flow API endpoint via POST request with input arguments.

  case "retell_create_conversation_flow":
    return retellRequest("/create-conversation-flow", "POST", args);

• src/index.ts:807-824 (schema)

  Input schema for the tool, specifying required 'name' and optional 'nodes' and 'edges' arrays.

  inputSchema: {
    type: "object",
    properties: {
      name: {
        type: "string",
        description: "Name for the conversation flow"
      },
      nodes: {
        type: "array",
        description: "Array of node configurations defining the flow"
      },
      edges: {
        type: "array",
        description: "Array of edge configurations connecting nodes"
      }
    },
    required: ["name"]
  }

• src/index.ts:804-825 (registration)

  Registration of the tool in the 'tools' array, which is returned by the ListTools handler for MCP tool discovery.

  {
    name: "retell_create_conversation_flow",
    description: "Create a new conversation flow for structured, node-based conversation design.",
    inputSchema: {
      type: "object",
      properties: {
        name: {
          type: "string",
          description: "Name for the conversation flow"
        },
        nodes: {
          type: "array",
          description: "Array of node configurations defining the flow"
        },
        edges: {
          type: "array",
          description: "Array of edge configurations connecting nodes"
        }
      },
      required: ["name"]
    }
  },

• src/index.ts:23-57 (helper)

  Shared helper function that performs authenticated HTTP requests to the Retell API, used by all tool handlers including this one.

  async function retellRequest(
    endpoint: string,
    method: string = "GET",
    body?: Record<string, unknown>
  ): Promise<unknown> {
    const apiKey = getApiKey();
  
    const headers: Record<string, string> = {
      "Authorization": `Bearer ${apiKey}`,
      "Content-Type": "application/json",
    };
  
    const options: RequestInit = {
      method,
      headers,
    };
  
    if (body && method !== "GET") {
      options.body = JSON.stringify(body);
    }
  
    const response = await fetch(`${RETELL_API_BASE}${endpoint}`, options);
  
    if (!response.ok) {
      const errorText = await response.text();
      throw new Error(`Retell API error (${response.status}): ${errorText}`);
    }
  
    // Handle 204 No Content
    if (response.status === 204) {
      return { success: true };
    }
  
    return response.json();
  }