diff --git a/packages/api/src/endpoints/openai/config.spec.ts b/packages/api/src/endpoints/openai/config.spec.ts
index ac4e825a00..5d6ffa60be 100644
--- a/packages/api/src/endpoints/openai/config.spec.ts
+++ b/packages/api/src/endpoints/openai/config.spec.ts
@@ -151,6 +151,114 @@ describe('getOpenAIConfig', () => {
     expect(result.tools).toEqual([{ type: 'web_search_preview' }]);
   });
 
+  it('should handle web_search from addParams overriding modelOptions', () => {
+    const modelOptions = {
+      model: 'gpt-5',
+      web_search: false,
+    };
+
+    const addParams = {
+      web_search: true,
+      customParam: 'value',
+    };
+
+    const result = getOpenAIConfig(mockApiKey, { modelOptions, addParams });
+
+    expect(result.llmConfig.useResponsesApi).toBe(true);
+    expect(result.tools).toEqual([{ type: 'web_search_preview' }]);
+    // web_search should not be in modelKwargs or llmConfig
+    expect((result.llmConfig as Record<string, unknown>).web_search).toBeUndefined();
+    expect(result.llmConfig.modelKwargs).toEqual({ customParam: 'value' });
+  });
+
+  it('should disable web_search when included in dropParams', () => {
+    const modelOptions = {
+      model: 'gpt-5',
+      web_search: true,
+    };
+
+    const result = getOpenAIConfig(mockApiKey, {
+      modelOptions,
+      dropParams: ['web_search'],
+    });
+
+    expect(result.llmConfig.useResponsesApi).toBeUndefined();
+    expect(result.tools).toEqual([]);
+  });
+
+  it('should handle web_search false from addParams', () => {
+    const modelOptions = {
+      model: 'gpt-5',
+      web_search: true,
+    };
+
+    const addParams = {
+      web_search: false,
+    };
+
+    const result = getOpenAIConfig(mockApiKey, { modelOptions, addParams });
+
+    expect(result.llmConfig.useResponsesApi).toBeUndefined();
+    expect(result.tools).toEqual([]);
+  });
+
+  it('should ignore non-boolean web_search values in addParams', () => {
+    const modelOptions = {
+      model: 'gpt-5',
+      web_search: true,
+    };
+
+    const addParams = {
+      web_search: 'string-value' as unknown,
+      temperature: 0.7,
+    };
+
+    const result = getOpenAIConfig(mockApiKey, { modelOptions, addParams });
+
+    // Should keep the original web_search from modelOptions since addParams value is not boolean
+    expect(result.llmConfig.useResponsesApi).toBe(true);
+    expect(result.tools).toEqual([{ type: 'web_search_preview' }]);
+    expect(result.llmConfig.temperature).toBe(0.7);
+    // web_search should not be added to modelKwargs
+    expect(result.llmConfig.modelKwargs).toBeUndefined();
+  });
+
+  it('should handle web_search with both addParams and dropParams', () => {
+    const modelOptions = {
+      model: 'gpt-5',
+    };
+
+    const addParams = {
+      web_search: true,
+    };
+
+    const result = getOpenAIConfig(mockApiKey, {
+      modelOptions,
+      addParams,
+      dropParams: ['web_search'], // dropParams takes precedence
+    });
+
+    expect(result.llmConfig.useResponsesApi).toBeUndefined();
+    expect(result.tools).toEqual([]);
+  });
+
+  it('should not add web_search to modelKwargs or llmConfig', () => {
+    const addParams = {
+      web_search: true,
+      customParam1: 'value1',
+      temperature: 0.5,
+    };
+
+    const result = getOpenAIConfig(mockApiKey, { addParams });
+
+    // web_search should trigger the tool but not appear in config
+    expect(result.llmConfig.useResponsesApi).toBe(true);
+    expect(result.tools).toEqual([{ type: 'web_search_preview' }]);
+    expect((result.llmConfig as Record<string, unknown>).web_search).toBeUndefined();
+    expect(result.llmConfig.temperature).toBe(0.5);
+    expect(result.llmConfig.modelKwargs).toEqual({ customParam1: 'value1' });
+  });
+
   it('should drop params for search models', () => {
     const modelOptions = {
       model: 'gpt-4o-search',
diff --git a/packages/api/src/endpoints/openai/llm.ts b/packages/api/src/endpoints/openai/llm.ts
index d508dcd1ed..c462b664ef 100644
--- a/packages/api/src/endpoints/openai/llm.ts
+++ b/packages/api/src/endpoints/openai/llm.ts
@@ -129,8 +129,17 @@ export function getOpenAILLMConfig({
     hasModelKwargs = true;
   }
 
+  let enableWebSearch = web_search;
+
   if (addParams && typeof addParams === 'object') {
     for (const [key, value] of Object.entries(addParams)) {
+      /** Handle web_search directly here instead of adding to modelKwargs or llmConfig */
+      if (key === 'web_search') {
+        if (typeof value === 'boolean') {
+          enableWebSearch = value;
+        }
+        continue;
+      }
       if (knownOpenAIParams.has(key)) {
         (llmConfig as Record<string, unknown>)[key] = value;
       } else {
@@ -166,7 +175,12 @@ export function getOpenAILLMConfig({
 
   const tools: BindToolsInput[] = [];
 
-  if (web_search) {
+  /** Check if web_search should be disabled via dropParams */
+  if (dropParams && dropParams.includes('web_search')) {
+    enableWebSearch = false;
+  }
+
+  if (enableWebSearch) {
     llmConfig.useResponsesApi = true;
     tools.push({ type: 'web_search_preview' });
   }