diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index 303ff11fdfd..9d98815cdad 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -1270,8 +1270,14 @@ export function options(input: {
     result["gateway"] = { caching: "auto" }
   }
 
-  if (input.model.api.npm === "@ai-sdk/azure" && input.model.api.id.includes("gpt-5.5")) {
-    result["reasoningSummary"] = "auto"
+  // Any gpt version above 5.4 in combination with azure does not support reasoningEffort
+  // so we should return early here.
+  const [, gptMajorVersion, gptMinorVersion] = input.model.api.id.match(/gpt-(\d+)\.(\d+)/) ?? []
+  const isGpt55OrNewer = Number(gptMajorVersion) > 5 || (Number(gptMajorVersion) === 5 && Number(gptMinorVersion) >= 5)
+  if (input.model.api.npm === "@ai-sdk/azure" && input.providerOptions?.useCompletionUrls) {
+    if (!isGpt55OrNewer) {
+      result["reasoningEffort"] = "medium"
+    }
     return result
   }
 
diff --git a/packages/opencode/test/provider/transform.test.ts b/packages/opencode/test/provider/transform.test.ts
index 0b88fa59dff..6e9efe06bb0 100644
--- a/packages/opencode/test/provider/transform.test.ts
+++ b/packages/opencode/test/provider/transform.test.ts
@@ -690,6 +690,16 @@ describe("ProviderTransform.options - gpt-5 reasoningEffort", () => {
 
     expect(result.reasoningEffort).toBeUndefined()
   })
+
+  test("gpt-5.6 should NOT set reasoningEffort", () => {
+    const result = ProviderTransform.options({
+      model: createModel("gpt-5.6"),
+      sessionID,
+      providerOptions: {},
+    })
+
+    expect(result.reasoningEffort).toBeUndefined()
+  })
 })
 
 describe("ProviderTransform.options - gateway", () => {