diff --git a/packages/ai/src/providers/openai-completions.ts b/packages/ai/src/providers/openai-completions.ts
index 8e80723f..c4332b3c 100644
--- a/packages/ai/src/providers/openai-completions.ts
+++ b/packages/ai/src/providers/openai-completions.ts
@@ -333,10 +333,12 @@ export const streamSimpleOpenAICompletions: StreamFunction<"openai-completions",
 
 	const base = buildBaseOptions(model, options, apiKey);
 	const reasoningEffort = supportsXhigh(model) ? options?.reasoning : clampReasoning(options?.reasoning);
+	const toolChoice = (options as OpenAICompletionsOptions | undefined)?.toolChoice;
 
 	return streamOpenAICompletions(model, context, {
 		...base,
 		reasoningEffort,
+		toolChoice,
 	} satisfies OpenAICompletionsOptions);
 };
 
diff --git a/packages/ai/test/openai-completions-tool-choice.test.ts b/packages/ai/test/openai-completions-tool-choice.test.ts
new file mode 100644
index 00000000..9bfeead1
--- /dev/null
+++ b/packages/ai/test/openai-completions-tool-choice.test.ts
@@ -0,0 +1,75 @@
+import { Type } from "@sinclair/typebox";
+import { describe, expect, it, vi } from "vitest";
+import type { Tool } from "../src/types.js";
+
+let lastParams: unknown;
+
+class FakeOpenAI {
+	chat = {
+		completions: {
+			create: async (params: unknown) => {
+				lastParams = params;
+				return {
+					async *[Symbol.asyncIterator]() {
+						yield {
+							choices: [{ delta: {}, finish_reason: "stop" }],
+							usage: {
+								prompt_tokens: 1,
+								completion_tokens: 1,
+								prompt_tokens_details: { cached_tokens: 0 },
+								completion_tokens_details: { reasoning_tokens: 0 },
+							},
+						};
+					},
+				};
+			},
+		},
+	};
+}
+
+vi.mock("openai", () => ({ default: FakeOpenAI }));
+
+describe("openai-completions tool_choice", () => {
+	it("forwards toolChoice from simple options to payload", async () => {
+		const { streamSimple } = await import("../src/stream.js");
+		const { getModel } = await import("../src/models.js");
+		const { compat: _compat, ...baseModel } = getModel("openai", "gpt-4o-mini")!;
+		const model = { ...baseModel, api: "openai-completions" } as const;
+		const tools: Tool[] = [
+			{
+				name: "ping",
+				description: "Ping tool",
+				parameters: Type.Object({
+					ok: Type.Boolean(),
+				}),
+			},
+		];
+		let payload: unknown;
+
+		await streamSimple(
+			model,
+			{
+				messages: [
+					{
+						role: "user",
+						content: "Call ping with ok=true",
+						timestamp: Date.now(),
+					},
+				],
+				tools,
+			},
+			{
+				apiKey: "test",
+				toolChoice: "required",
+				onPayload: (params: unknown) => {
+					payload = params;
+				},
+			} as unknown as Parameters<typeof streamSimple>[2],
+		).result();
+
+		const params = (payload ?? lastParams) as { tool_choice?: string; tools?: unknown[] };
+		expect(params.tool_choice).toBe("required");
+		expect(Array.isArray(params.tools)).toBe(true);
+		expect(params.tools?.length ?? 0).toBeGreaterThan(0);
+	});
+});