Retell AI MCP Server

Instructions

Implementation Reference

• src/index.ts:1063-1080 (schema)

  Schema definition for the retell_create_batch_test tool, including input schema for agent_id and test_cases.

  {
    name: "retell_create_batch_test",
    description: "Run automated test scenarios against an agent.",
    inputSchema: {
      type: "object",
      properties: {
        agent_id: {
          type: "string",
          description: "The agent ID to test"
        },
        test_cases: {
          type: "array",
          description: "Array of test case configurations"
        }
      },
      required: ["agent_id", "test_cases"]
    }
  },

• src/index.ts:1255-1256 (handler)

  Handler case in executeTool function that executes the tool by calling retellRequest to the /create-batch-test API endpoint.

  case "retell_create_batch_test":
    return retellRequest("/create-batch-test", "POST", args);

• src/index.ts:23-57 (helper)

  Generic retellRequest helper function that performs authenticated API calls to Retell AI backend, used by all tool handlers.

  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)

  Registration of the tool list handler, which exposes the tools array (including retell_create_batch_test) via MCP ListToolsRequest.

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