diff --git a/.changeset/bright-meals-add.md b/.changeset/bright-meals-add.md
new file mode 100644
index 000000000..2353bebf4
--- /dev/null
+++ b/.changeset/bright-meals-add.md
@@ -0,0 +1,5 @@
+---
+"@browserbasehq/stagehand": patch
+---
+
+feat: adding gpt 5.1 to stagehand
diff --git a/packages/core/lib/v3/llm/aisdk.ts b/packages/core/lib/v3/llm/aisdk.ts
index ec8ac23fe..d437766fc 100644
--- a/packages/core/lib/v3/llm/aisdk.ts
+++ b/packages/core/lib/v3/llm/aisdk.ts
@@ -127,6 +127,7 @@ export class AISdkClient extends LLMClient {
 
     let objectResponse: Awaited<ReturnType<typeof generateObject>>;
     const isGPT5 = this.model.modelId.includes("gpt-5");
+    const isGPT51 = this.model.modelId.includes("gpt-5.1");
     if (options.response_model) {
       try {
         objectResponse = await generateObject({
@@ -138,7 +139,7 @@ export class AISdkClient extends LLMClient {
             ? {
                 openai: {
                   textVerbosity: "low", // Making these the default for gpt-5 for now
-                  reasoningEffort: "minimal",
+                  reasoningEffort: isGPT51 ? "low" : "minimal",
                 },
               }
             : undefined,
diff --git a/packages/evals/lib/AISdkClientWrapped.ts b/packages/evals/lib/AISdkClientWrapped.ts
index 3f13baf30..669aef7a2 100644
--- a/packages/evals/lib/AISdkClientWrapped.ts
+++ b/packages/evals/lib/AISdkClientWrapped.ts
@@ -133,6 +133,7 @@ export class AISdkClientWrapped extends LLMClient {
 
     let objectResponse: Awaited<ReturnType<typeof generateObject>>;
     const isGPT5 = this.model.modelId.includes("gpt-5");
+    const isGPT51 = this.model.modelId.includes("gpt-5.1");
     if (options.response_model) {
       try {
         objectResponse = await generateObject({
@@ -144,7 +145,7 @@ export class AISdkClientWrapped extends LLMClient {
             ? {
                 openai: {
                   textVerbosity: "low", // Making these the default for gpt-5 for now
-                  reasoningEffort: "minimal",
+                  reasoningEffort: isGPT51 ? "low" : "minimal",
                 },
               }
             : undefined,