Retell AI MCP Server

Instructions

Implementation Reference

• src/index.ts:1189-1190 (handler)

  Handler logic for retell_get_chat_agent tool: makes a GET request to Retell API endpoint `/get-chat-agent/${agent_id}` using the retellRequest helper.

  case "retell_get_chat_agent":
    return retellRequest(`/get-chat-agent/${args.agent_id}`, "GET");

• src/index.ts:642-655 (schema)

  Tool definition including name, description, and input schema (requires agent_id string). This is part of the tools array used for MCP tool listing.

  {
    name: "retell_get_chat_agent",
    description: "Retrieve details of a specific chat agent.",
    inputSchema: {
      type: "object",
      properties: {
        agent_id: {
          type: "string",
          description: "The chat agent ID"
        }
      },
      required: ["agent_id"]
    }
  },

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

  MCP server handler for listing tools, which returns the tools array containing the retell_get_chat_agent definition.

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

• src/index.ts:23-57 (helper)

  Generic helper function for making authenticated HTTP requests to the Retell AI API, used by the tool handler.

  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();
  }