diff --git a/components/simple-transcription/index.js b/components/simple-transcription/index.js
index 769dd9fd..d6138436 100644
--- a/components/simple-transcription/index.js
+++ b/components/simple-transcription/index.js
@@ -872,7 +872,20 @@ export default class SimpleTranscriptionInterface extends HTMLElement {
         const projectPage = TPEN.activeProject?.layers
           ?.flatMap(layer => layer.pages || [])
           .find(p => p.id.split('/').pop() === currentPageId)
-        
+
+        // Forward auth to TPEN-Prompts only; other tools do not receive the token.
+        if (tool.toolName === 'tpen-prompts') {
+          iframe.contentWindow?.postMessage(
+            {
+              type: "AUTH_TOKEN",
+              token: this.userToken ?? null,
+              projectID: TPEN.screen?.projectInQuery ?? null,
+              pageID: currentPageId ?? null
+            },
+            this._iframeOrigin
+          )
+        }
+
         iframe.contentWindow?.postMessage(
           {
             type: "MANIFEST_CANVAS_ANNOTATIONPAGE_ANNOTATION",
diff --git a/interfaces/transcription/index.js b/interfaces/transcription/index.js
index d9b9609b..74cbb702 100644
--- a/interfaces/transcription/index.js
+++ b/interfaces/transcription/index.js
@@ -402,6 +402,19 @@ export default class TranscriptionInterface extends HTMLElement {
         this._iframeOrigin = new URL(tool.url).origin
       
       iframe.addEventListener('load', () => {
+        // Forward auth to TPEN-Prompts only; other tools do not receive the token.
+        if (tool.toolName === 'tpen-prompts') {
+          iframe.contentWindow?.postMessage(
+            {
+              type: "AUTH_TOKEN",
+              token: this.userToken ?? null,
+              projectID: TPEN.screen?.projectInQuery ?? null,
+              pageID: TPEN.screen?.pageInQuery ?? null
+            },
+            this._iframeOrigin
+          )
+        }
+
         iframe.contentWindow?.postMessage(
           {
             type: "MANIFEST_CANVAS_ANNOTATIONPAGE_ANNOTATION",