diff --git a/functions/prompts/analyze-collocation.prompt b/functions/prompts/analyze-collocation.prompt
index a101ca0..190821e 100644
--- a/functions/prompts/analyze-collocation.prompt
+++ b/functions/prompts/analyze-collocation.prompt
@@ -1,5 +1,5 @@
 ---
-model: vertexai/gemini-2.0-flash-001
+model: vertexai/gemini-3-flash-preview
 input:
   schema:
     collocation: string
diff --git a/functions/prompts/analyze-image.prompt b/functions/prompts/analyze-image.prompt
index c2933bd..e229dd9 100644
--- a/functions/prompts/analyze-image.prompt
+++ b/functions/prompts/analyze-image.prompt
@@ -1,10 +1,12 @@
 ---
-model: vertexai/gemini-2.0-flash-001
+model: vertexai/gemini-2.5-flash
+config:
+  maxOutputTokens: 65536
 input:
   schema:
     base64ImageUrl: string
 output:
   schema: ImageAnalysisSchema
 ---
-Read the Chinese text in this image: {{media url=base64ImageUrl}}, split it into sentences, and then explain it, including an English translation for each sentence and any relevant grammar rules.
+Read the Chinese text in this image: {{media url=base64ImageUrl}}. Split the complete text into every individual sentence, providing pinyin and an English translation for each one. Then provide an overall plain-text explanation of the passage and any relevant grammar rules.
 If the image contains good English translations of the Chinese text, use those verbatim.
diff --git a/functions/prompts/explain-chinese.prompt b/functions/prompts/explain-chinese.prompt
index 36ba166..745ea71 100644
--- a/functions/prompts/explain-chinese.prompt
+++ b/functions/prompts/explain-chinese.prompt
@@ -1,5 +1,5 @@
 ---
-model: vertexai/gemini-2.0-flash-001
+model: vertexai/gemini-3-flash-preview
 input:
   schema:
     text: string
diff --git a/functions/prompts/explain-english.prompt b/functions/prompts/explain-english.prompt
index f92836b..0a04b1a 100644
--- a/functions/prompts/explain-english.prompt
+++ b/functions/prompts/explain-english.prompt
@@ -1,5 +1,5 @@
 ---
-model: vertexai/gemini-2.0-flash-001
+model: vertexai/gemini-3-flash-preview
 input:
   schema:
     text: string
diff --git a/functions/prompts/explain-word-in-context.prompt b/functions/prompts/explain-word-in-context.prompt
index 4f2996a..0b576e0 100644
--- a/functions/prompts/explain-word-in-context.prompt
+++ b/functions/prompts/explain-word-in-context.prompt
@@ -1,5 +1,5 @@
 ---
-model: vertexai/gemini-2.0-flash-001
+model: vertexai/gemini-3-flash-preview
 input:
   schema: ExplainWordInContextInputSchema
 output:
diff --git a/functions/prompts/generate-chinese-sentences.prompt b/functions/prompts/generate-chinese-sentences.prompt
index eab9b69..48ebbbd 100644
--- a/functions/prompts/generate-chinese-sentences.prompt
+++ b/functions/prompts/generate-chinese-sentences.prompt
@@ -1,5 +1,5 @@
 ---
-model: vertexai/gemini-2.0-flash-001
+model: vertexai/gemini-3-flash-preview
 input:
   schema: GenerateChineseSentencesInputSchema
 output:
diff --git a/functions/src/genkit-eval.ts b/functions/src/genkit-eval.ts
index 80a2f91..d9f894d 100644
--- a/functions/src/genkit-eval.ts
+++ b/functions/src/genkit-eval.ts
@@ -179,7 +179,7 @@ export const grammarExplanationQualityEvaluator = ai.defineEvaluator(
             JSON.stringify(datapoint.output);
 
         const { output: evalResult } = await ai.generate({
-            model: vertexAI.model('gemini-3-pro-preview'),
+            model: vertexAI.model('gemini-3.1-pro-preview'),
             prompt: `You are evaluating a Chinese language learning tool's output quality.
 
 Input (Chinese text to explain): ${input}
@@ -248,7 +248,7 @@ export const sentenceGenerationQualityEvaluator = ai.defineEvaluator(
             JSON.stringify(datapoint.output);
 
         const { output: evalResult } = await ai.generate({
-            model: vertexAI.model('gemini-3-pro-preview'),
+            model: vertexAI.model('gemini-3.1-pro-preview'),
             prompt: `You are evaluating generated Chinese example sentences for a language learning app.
 
 Input (word and definitions): ${input}