diff --git a/providers/openai/language_model.go b/providers/openai/language_model.go
index f37cee5280c9b299e17caded29c673e003477dcf..9df357ac878adbe839f914d91acb0e950a1cf4e3 100644
--- a/providers/openai/language_model.go
+++ b/providers/openai/language_model.go
@@ -619,6 +619,10 @@ func toOpenAiTools(tools []fantasy.Tool, toolChoice *fantasy.ToolChoice) (openAi
 		openAiToolChoice = &openai.ChatCompletionToolChoiceOptionUnionParam{
 			OfAuto: param.NewOpt("none"),
 		}
+	case fantasy.ToolChoiceRequired:
+		openAiToolChoice = &openai.ChatCompletionToolChoiceOptionUnionParam{
+			OfAuto: param.NewOpt("required"),
+		}
 	default:
 		openAiToolChoice = &openai.ChatCompletionToolChoiceOptionUnionParam{
 			OfFunctionToolChoice: &openai.ChatCompletionNamedToolChoiceParam{
diff --git a/providers/openai/openai_test.go b/providers/openai/openai_test.go
index 97296fd974d9cb069649e3dcdb167e88994dfe0b..97e5a8e9fe97e452749411ca8cc635db221be503 100644
--- a/providers/openai/openai_test.go
+++ b/providers/openai/openai_test.go
@@ -1288,6 +1288,65 @@ func TestDoGenerate(t *testing.T) {
 		require.Equal(t, `{"value":"Spark"}`, toolCall.Input)
 	})
 
+	t.Run("should handle ToolChoiceRequired", func(t *testing.T) {
+		t.Parallel()
+
+		server := newMockServer()
+		defer server.close()
+
+		server.prepareJSONResponse(map[string]any{
+			"content": "",
+		})
+
+		provider, err := New(
+			WithAPIKey("test-api-key"),
+			WithBaseURL(server.server.URL),
+		)
+		require.NoError(t, err)
+		model, _ := provider.LanguageModel(t.Context(), "gpt-3.5-turbo")
+
+		_, err = model.Generate(context.Background(), fantasy.Call{
+			Prompt: testPrompt,
+			Tools: []fantasy.Tool{
+				fantasy.FunctionTool{
+					Name: "test-tool",
+					InputSchema: map[string]any{
+						"type": "object",
+						"properties": map[string]any{
+							"value": map[string]any{
+								"type": "string",
+							},
+						},
+						"required":             []string{"value"},
+						"additionalProperties": false,
+						"$schema":              "http://json-schema.org/draft-07/schema#",
+					},
+				},
+			},
+			ToolChoice: &[]fantasy.ToolChoice{fantasy.ToolChoiceRequired}[0],
+		})
+
+		require.NoError(t, err)
+		require.Len(t, server.calls, 1)
+
+		call := server.calls[0]
+		require.Equal(t, "gpt-3.5-turbo", call.body["model"])
+
+		// Verify tool is present
+		tools := call.body["tools"].([]any)
+		require.Len(t, tools, 1)
+
+		tool := tools[0].(map[string]any)
+		require.Equal(t, "function", tool["type"])
+
+		function := tool["function"].(map[string]any)
+		require.Equal(t, "test-tool", function["name"])
+
+		// Verify tool_choice is set to "required" (not a function name)
+		toolChoice := call.body["tool_choice"]
+		require.Equal(t, "required", toolChoice)
+	})
+
 	t.Run("should parse annotations/citations", func(t *testing.T) {
 		t.Parallel()