diff --git a/src/components/HarnessWizard.tsx b/src/components/HarnessWizard.tsx
index ee484645b..384fb9e24 100644
--- a/src/components/HarnessWizard.tsx
+++ b/src/components/HarnessWizard.tsx
@@ -671,8 +671,8 @@ const MODEL_PROVIDERS: {
       },
       {
         key: "apiBase",
-        name: "API base URL",
-        helpText: "optional · the provider API endpoint",
+        name: "Custom API base URL",
+        helpText: "optional · leave blank to use the model provider's default endpoint",
         placeholder: "https://…",
         required: false,
         requiredError: "",
diff --git a/src/handlers/harness/create/create.screen.test.tsx b/src/handlers/harness/create/create.screen.test.tsx
index a446aaac7..d09189670 100644
--- a/src/handlers/harness/create/create.screen.test.tsx
+++ b/src/handlers/harness/create/create.screen.test.tsx
@@ -245,6 +245,8 @@ describe("harness create wizard", () => {
     await r.press("down"); // litellm
     await waitForText(r.lastFrame, "● litellm");
     await r.press("return"); // focus the model id field
+    await waitForText(r.lastFrame, "Custom API base URL");
+    expect(r.lastFrame()).toContain("leave blank to use the model provider's default endpoint");
     await r.write("anthropic/claude-3-sonnet");
     await r.press("return"); // api key arn — optional, leave empty
     await r.press("return"); // api base url — optional, leave empty
diff --git a/src/handlers/project/HarnessModelField.tsx b/src/handlers/project/HarnessModelField.tsx
index 737d37ac4..1a2536904 100644
--- a/src/handlers/project/HarnessModelField.tsx
+++ b/src/handlers/project/HarnessModelField.tsx
@@ -107,7 +107,7 @@ export function harnessModelSummary(values: HarnessModelValues): Record<string,
     provider: providerLabel(values.provider),
     model: model.modelId,
     ...(model.apiKeyArn !== undefined && { "API key ARN": model.apiKeyArn }),
-    ...(model.apiBase !== undefined && { "API base URL": model.apiBase }),
+    ...(model.apiBase !== undefined && { "Custom API base URL": model.apiBase }),
   };
 }
 
@@ -159,8 +159,8 @@ function modelFields(provider: HarnessModelProvider): ModelField[] {
   if (provider === "lite_llm") {
     fields.push({
       key: "apiBase",
-      name: "API base URL",
-      helpText: "optional · the provider API endpoint",
+      name: "Custom API base URL",
+      helpText: "optional · leave blank to use the model provider's default endpoint",
       placeholder: "https://…",
       required: false,
       requiredError: "",
diff --git a/src/handlers/project/add/harness/harness.screen.test.tsx b/src/handlers/project/add/harness/harness.screen.test.tsx
index d7dbb2021..eed9c1109 100644
--- a/src/handlers/project/add/harness/harness.screen.test.tsx
+++ b/src/handlers/project/add/harness/harness.screen.test.tsx
@@ -237,7 +237,10 @@ describe("project add harness wizard", () => {
     await screen.press("return");
 
     // LiteLLM is the one provider with an API base; its key is optional.
-    await waitForText(screen.lastFrame, "API base URL");
+    await waitForText(screen.lastFrame, "Custom API base URL");
+    expect(screen.lastFrame()).toContain(
+      "leave blank to use the model provider's default endpoint",
+    );
     expect(screen.lastFrame()).toContain(`bedrock/${DEFAULT_HARNESS_MODEL.modelId}`);
     await screen.press("return"); // keep the default model ID
     await screen.press("return"); // no API key ARN
@@ -247,7 +250,7 @@ describe("project add harness wizard", () => {
     await waitForText(screen.lastFrame, "this harness will be added to agentcore.json");
     const review = flatFrame(screen.lastFrame);
     expect(review).toContain("provider litellm");
-    expect(review).toContain("API base URL https://llm.example.com/v1");
+    expect(review).toContain("Custom API base URL https://llm.example.com/v1");
     expect(review).not.toContain("API key ARN");
     await screen.press("return");
 
diff --git a/src/handlers/project/create/create.screen.test.tsx b/src/handlers/project/create/create.screen.test.tsx
index d14879562..5573f5df8 100644
--- a/src/handlers/project/create/create.screen.test.tsx
+++ b/src/handlers/project/create/create.screen.test.tsx
@@ -345,7 +345,10 @@ describe("project create wizard", () => {
     const scrolled = await settledLines();
     expect(scrolled[firstContentLine]).not.toBe(" choose a model provider");
     expect(scrolled).toContain(" model ID");
-    expect(scrolled).toContain(" API base URL");
+    expect(scrolled).toContain(" Custom API base URL");
+    expect(scrolled.join("\n")).toContain(
+      "leave blank to use the model provider's default endpoint",
+    );
 
     // Moving back up to fields that are still visible does not shift the view.
     await r.press("up");