diff --git a/apps/sim/providers/openai/utils.test.ts b/apps/sim/providers/openai/utils.test.ts
index ae976233930..a2c574a570f 100644
--- a/apps/sim/providers/openai/utils.test.ts
+++ b/apps/sim/providers/openai/utils.test.ts
@@ -6,6 +6,7 @@ import { describe, expect, it } from 'vitest'
 import { ResolvedSecretTraceRegistry } from '@/executor/utils/resolved-secret-trace-registry'
 import {
   buildResponsesInputFromMessages,
+  convertToolsToResponses,
   parseResponsesUsage,
   toOpenAIModelUsage,
 } from '@/providers/openai/utils'
@@ -155,3 +156,28 @@ describe('buildResponsesInputFromMessages', () => {
     ])
   })
 })
+
+describe('convertToolsToResponses', () => {
+  it.each(['wrapped', 'flat'] as const)(
+    'preserves optional inputs on %s tool definitions without implicit strict normalization',
+    (shape) => {
+      const parameters = {
+        type: 'object',
+        properties: {
+          fileId: { type: 'string' },
+          folderPaths: { type: 'array', items: { type: 'string' } },
+          offset: { type: 'number' },
+        },
+        required: ['fileId'],
+      }
+      const tool = { name: 'file_get_content', description: 'Read selected file text', parameters }
+      const converted = convertToolsToResponses([
+        shape === 'wrapped' ? { type: 'function', function: tool } : tool,
+      ])
+
+      expect(converted).toEqual([{ type: 'function', strict: false, ...tool }])
+      expect(converted[0].parameters).toBe(parameters)
+      expect(parameters.required).toEqual(['fileId'])
+    }
+  )
+})
diff --git a/apps/sim/providers/openai/utils.ts b/apps/sim/providers/openai/utils.ts
index 0586bf8741f..536f3c94634 100644
--- a/apps/sim/providers/openai/utils.ts
+++ b/apps/sim/providers/openai/utils.ts
@@ -140,6 +140,7 @@ export async function* iterateResponsesStreamEvents(
 
 export interface ResponsesToolDefinition {
   type: 'function'
+  strict: false
   name: string
   description?: string
   parameters?: Record<string, unknown>
@@ -200,7 +201,8 @@ export function buildResponsesInputFromMessages(
 }
 
 /**
- * Converts tool definitions to the Responses API format.
+ * Converts tool definitions without changing their required and optional inputs.
+ * Responses otherwise attempts strict normalization, which can require optional fields.
  */
 export function convertToolsToResponses(
   tools: Array<{
@@ -220,6 +222,7 @@ export function convertToolsToResponses(
 
       return {
         type: 'function' as const,
+        strict: false as const,
         name,
         description: tool.function?.description ?? tool.description,
         parameters: tool.function?.parameters ?? tool.parameters,