diff --git a/genkit-tools/cli/src/commands/start.ts b/genkit-tools/cli/src/commands/start.ts
index afb6fdb154..151f468f93 100644
--- a/genkit-tools/cli/src/commands/start.ts
+++ b/genkit-tools/cli/src/commands/start.ts
@@ -26,7 +26,7 @@ interface RunOptions {
   noui?: boolean;
   port?: string;
   open?: boolean;
-  experimentalRealtimeTelemetry?: boolean;
+  disableRealtimeTelemetry?: boolean;
 }
 
 /** Command to run code in dev mode and/or the Dev UI. */
@@ -36,8 +36,8 @@ export const start = new Command('start')
   .option('-p, --port <port>', 'port for the Dev UI')
   .option('-o, --open', 'Open the browser on UI start up')
   .option(
-    '--experimental-realtime-telemetry',
-    'Enable real-time telemetry streaming (experimental)'
+    '--disable-realtime-telemetry',
+    'Disable real-time telemetry streaming'
   )
   .action(async (options: RunOptions) => {
     const projectRoot = await findProjectRoot();
@@ -55,7 +55,7 @@ export const start = new Command('start')
         projectRoot,
         start.args[0],
         start.args.slice(1),
-        { enableRealtimeTelemetry: options.experimentalRealtimeTelemetry }
+        { disableRealtimeTelemetry: options.disableRealtimeTelemetry }
       );
       manager = result.manager;
       processPromise = result.processPromise;
diff --git a/genkit-tools/cli/src/utils/manager-utils.ts b/genkit-tools/cli/src/utils/manager-utils.ts
index bb55ef3351..187e32a116 100644
--- a/genkit-tools/cli/src/utils/manager-utils.ts
+++ b/genkit-tools/cli/src/utils/manager-utils.ts
@@ -67,7 +67,7 @@ export async function startManager(
 }
 
 export interface DevProcessManagerOptions {
-  enableRealtimeTelemetry?: boolean;
+  disableRealtimeTelemetry?: boolean;
 }
 
 export async function startDevProcessManager(
@@ -77,11 +77,12 @@ export async function startDevProcessManager(
   options?: DevProcessManagerOptions
 ): Promise<{ manager: RuntimeManager; processPromise: Promise<void> }> {
   const telemetryServerUrl = await resolveTelemetryServer(projectRoot);
+  const disableRealtimeTelemetry = options?.disableRealtimeTelemetry ?? false;
   const envVars: Record<string, string> = {
     GENKIT_TELEMETRY_SERVER: telemetryServerUrl,
     GENKIT_ENV: 'dev',
   };
-  if (options?.enableRealtimeTelemetry) {
+  if (!disableRealtimeTelemetry) {
     envVars.GENKIT_ENABLE_REALTIME_TELEMETRY = 'true';
   }
   const processManager = new ProcessManager(command, args, envVars);
@@ -90,7 +91,7 @@ export async function startDevProcessManager(
     manageHealth: true,
     projectRoot,
     processManager,
-    enableRealtimeTelemetry: options?.enableRealtimeTelemetry,
+    disableRealtimeTelemetry,
   });
   const processPromise = processManager.start();
   return { manager, processPromise };
diff --git a/genkit-tools/common/src/manager/manager.ts b/genkit-tools/common/src/manager/manager.ts
index ac1ba913e5..7b20698644 100644
--- a/genkit-tools/common/src/manager/manager.ts
+++ b/genkit-tools/common/src/manager/manager.ts
@@ -60,13 +60,13 @@ interface RuntimeManagerOptions {
   projectRoot: string;
   /** An optional process manager for the main application process. */
   processManager?: ProcessManager;
-  /** Whether realtime telemetry streaming is enabled. */
-  enableRealtimeTelemetry?: boolean;
+  /** Whether to disable realtime telemetry streaming. Defaults to false. */
+  disableRealtimeTelemetry?: boolean;
 }
 
 export class RuntimeManager {
   readonly processManager?: ProcessManager;
-  readonly enableRealtimeTelemetry: boolean;
+  readonly disableRealtimeTelemetry: boolean;
   private filenameToRuntimeMap: Record<string, RuntimeInfo> = {};
   private filenameToDevUiMap: Record<string, DevToolsInfo> = {};
   private idToFileMap: Record<string, string> = {};
@@ -79,10 +79,10 @@ export class RuntimeManager {
     private manageHealth: boolean,
     readonly projectRoot: string,
     processManager?: ProcessManager,
-    enableRealtimeTelemetry?: boolean
+    disableRealtimeTelemetry?: boolean
   ) {
     this.processManager = processManager;
-    this.enableRealtimeTelemetry = enableRealtimeTelemetry ?? false;
+    this.disableRealtimeTelemetry = disableRealtimeTelemetry ?? false;
   }
 
   /**
@@ -94,7 +94,7 @@ export class RuntimeManager {
       options.manageHealth ?? true,
       options.projectRoot,
       options.processManager,
-      options.enableRealtimeTelemetry
+      options.disableRealtimeTelemetry
     );
     await manager.setupRuntimesWatcher();
     await manager.setupDevUiWatcher();
diff --git a/genkit-tools/common/src/server/server.ts b/genkit-tools/common/src/server/server.ts
index 2d2ec7b539..5ef7caf3ff 100644
--- a/genkit-tools/common/src/server/server.ts
+++ b/genkit-tools/common/src/server/server.ts
@@ -80,12 +80,12 @@ export function startServer(manager: RuntimeManager, port: number) {
 
       // When realtime telemetry is disabled, flush headers immediately.
       // The trace ID will be available in the response body.
-      if (!manager.enableRealtimeTelemetry) {
+      if (manager.disableRealtimeTelemetry) {
         res.flushHeaders();
       }
 
       try {
-        const onTraceIdCallback = manager.enableRealtimeTelemetry
+        const onTraceIdCallback = !manager.disableRealtimeTelemetry
           ? (traceId: string) => {
               // Set trace ID header and flush - this fires before response body
               res.setHeader('X-Genkit-Trace-Id', traceId);
@@ -127,12 +127,12 @@ export function startServer(manager: RuntimeManager, port: number) {
 
       // When realtime telemetry is disabled, flush headers immediately.
       // The trace ID will be available in the response body.
-      if (!manager.enableRealtimeTelemetry) {
+      if (manager.disableRealtimeTelemetry) {
         res.flushHeaders();
       }
 
       try {
-        const onTraceIdCallback = manager.enableRealtimeTelemetry
+        const onTraceIdCallback = !manager.disableRealtimeTelemetry
           ? (traceId: string) => {
               // Set trace ID header and flush - this fires before first chunk
               res.setHeader('X-Genkit-Trace-Id', traceId);