Retell AI MCP Server

Instructions

Implementation Reference

• src/index.ts:1229-1230 (handler)

  The switch case handler in the executeTool function that executes the tool by calling the generic retellRequest helper to POST to the Retell API's /create-knowledge-base endpoint with the provided arguments.

  case "retell_create_knowledge_base":
    return retellRequest("/create-knowledge-base", "POST", args);

• src/index.ts:890-907 (schema)

  The tool registration object in the tools array, including name, description, and inputSchema for parameter validation in MCP.

  {
    name: "retell_create_knowledge_base",
    description: "Create a new knowledge base for providing context to agents.",
    inputSchema: {
      type: "object",
      properties: {
        knowledge_base_name: {
          type: "string",
          description: "Name for the knowledge base"
        },
        enable_auto_refresh: {
          type: "boolean",
          description: "Whether to automatically refresh sources"
        }
      },
      required: ["knowledge_base_name"]
    }
  },

• src/index.ts:23-57 (helper)

  Generic helper function for making authenticated API requests to Retell AI, 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();
  }

• src/index.ts:1283-1285 (registration)

  MCP server request handler for ListToolsRequestSchema that returns the tools array containing this tool's definition.

  server.setRequestHandler(ListToolsRequestSchema, async () => {
    return { tools };
  });