diff --git a/packages/api/src/agents/__tests__/run-summarization.test.ts b/packages/api/src/agents/__tests__/run-summarization.test.ts
index 7d22511c21..ba31a0cdac 100644
--- a/packages/api/src/agents/__tests__/run-summarization.test.ts
+++ b/packages/api/src/agents/__tests__/run-summarization.test.ts
@@ -205,6 +205,39 @@ beforeEach(() => {
   jest.clearAllMocks();
 });
 
+// ---------------------------------------------------------------------------
+// Suite: custom endpoint stream usage defaults
+// ---------------------------------------------------------------------------
+describe('custom endpoint stream usage defaults', () => {
+  it('disables streamUsage by default for OpenAI-compatible custom endpoints', async () => {
+    const agents = await callAndCapture({
+      agents: [makeAgent({ endpoint: 'LiteLLM' })],
+    });
+    const clientOptions = agents[0].clientOptions as Record<string, unknown>;
+
+    expect(clientOptions.streamUsage).toBe(false);
+    expect(clientOptions.usage).toBe(true);
+  });
+
+  it('respects explicit streamUsage from endpoint-resolved model parameters', async () => {
+    const agents = await callAndCapture({
+      agents: [
+        makeAgent({
+          endpoint: 'LiteLLM',
+          model_parameters: {
+            model: 'gpt-4o',
+            streamUsage: true,
+          },
+        }),
+      ],
+    });
+    const clientOptions = agents[0].clientOptions as Record<string, unknown>;
+
+    expect(clientOptions.streamUsage).toBe(true);
+    expect(clientOptions.usage).toBe(true);
+  });
+});
+
 // ---------------------------------------------------------------------------
 // Suite 1: reserveRatio
 // ---------------------------------------------------------------------------
diff --git a/packages/api/src/agents/run.ts b/packages/api/src/agents/run.ts
index b0cc3105b6..e01f123e6a 100644
--- a/packages/api/src/agents/run.ts
+++ b/packages/api/src/agents/run.ts
@@ -804,6 +804,10 @@ export async function createRun({
     );
 
     const modelParameters = normalizeAgentModelParameters(agent.model_parameters);
+    const hasExplicitStreamUsage = Object.prototype.hasOwnProperty.call(
+      modelParameters ?? {},
+      'streamUsage',
+    );
     const llmConfig = Object.assign(
       {
         provider,
@@ -847,7 +851,9 @@ export async function createRun({
       customProviders.has(agent.provider) ||
       (agent.provider === Providers.OPENAI && agent.endpoint !== agent.provider)
     ) {
-      llmConfig.streamUsage = false;
+      if (!hasExplicitStreamUsage) {
+        llmConfig.streamUsage = false;
+      }
       llmConfig.usage = true;
     }