diff --git a/components/model/claude/claude.go b/components/model/claude/claude.go
index a8da5a321..adb70ab29 100644
--- a/components/model/claude/claude.go
+++ b/components/model/claude/claude.go
@@ -507,6 +507,15 @@ func toAnthropicToolParam(tools []*schema.ToolInfo) ([]anthropic.ToolUnionParam,
 				Properties: s.Properties,
 				Required:   s.Required,
 			}
+			// Pass through additionalProperties from the JSON Schema if present.
+			// This is required for strict tool use mode on some providers (e.g. Bedrock).
+			if s.AdditionalProperties != nil {
+				apBytes, _ := json.Marshal(s.AdditionalProperties)
+				var ap any
+				if json.Unmarshal(apBytes, &ap) == nil {
+					inputSchema.ExtraFields = map[string]any{"additionalProperties": ap}
+				}
+			}
 		}
 
 		toolParam := &anthropic.ToolParam{
@@ -515,6 +524,13 @@ func toAnthropicToolParam(tools []*schema.ToolInfo) ([]anthropic.ToolUnionParam,
 			InputSchema: inputSchema,
 		}
 
+		// Support strict tool use via ToolInfo.Extra["strict"] = true.
+		// When enabled, the API guarantees that tool call inputs conform
+		// to the declared JSON Schema exactly (no type coercion).
+		if strict, ok := tool.Extra["strict"].(bool); ok && strict {
+			toolParam.Strict = param.NewOpt(true)
+		}
+
 		if isBreakpointTool(tool) {
 			toolParam.CacheControl = newCacheControlParam(getToolBreakpointCacheControl(tool))
 		}
diff --git a/components/model/claude/claude_test.go b/components/model/claude/claude_test.go
index 7e28cf776..3c93f8a6a 100644
--- a/components/model/claude/claude_test.go
+++ b/components/model/claude/claude_test.go
@@ -389,6 +389,29 @@ func TestWithTools(t *testing.T) {
 	assert.Equal(t, "test tool name", ncm.(*ChatModel).origTools[0].Name)
 }
 
+func TestToAnthropicToolParam_Strict(t *testing.T) {
+	tools := []*schema.ToolInfo{
+		{
+			Name:  "strict_tool",
+			Desc:  "a tool with strict mode",
+			Extra: map[string]any{"strict": true},
+		},
+		{
+			Name: "normal_tool",
+			Desc: "a tool without strict mode",
+		},
+	}
+	result, err := toAnthropicToolParam(tools)
+	assert.NoError(t, err)
+	assert.Len(t, result, 2)
+
+	// First tool should have strict=true
+	assert.True(t, result[0].OfTool.Strict.Value)
+
+	// Second tool should not have strict set
+	assert.False(t, result[1].OfTool.Strict.Valid())
+}
+
 func TestPopulateContentBlockBreakPoint(t *testing.T) {
 	block := anthropic.NewTextBlock("input")
 	populateContentBlockBreakPoint(block, nil)
diff --git a/libs/acl/openai/chat_model.go b/libs/acl/openai/chat_model.go
index 4b3f98f25..c2f930ddb 100644
--- a/libs/acl/openai/chat_model.go
+++ b/libs/acl/openai/chat_model.go
@@ -666,6 +666,7 @@ func (c *Client) genRequest(ctx context.Context, in []*schema.Message, opts ...m
 				Function: &openai.FunctionDefinition{
 					Name:        t.Function.Name,
 					Description: t.Function.Description,
+					Strict:      dereferenceOrZero(t.Function.Strict),
 					Parameters:  t.Function.Parameters,
 				},
 			}
@@ -1066,20 +1067,20 @@ func populateToolChoice(req *openai.ChatCompletionRequest, tc *schema.ToolChoice
 		}
 
 		var onlyOneToolName string
-		if len(allowedToolNames) == 1 {
-			onlyOneToolName = allowedToolNames[0]
-		} else if len(req.Tools) == 1 {
+		if len(allowedToolNames) == 0 && len(req.Tools) == 1 {
 			onlyOneToolName = req.Tools[0].Function.Name
 		}
 
 		if onlyOneToolName != "" {
-			req.ToolChoice = openai.ToolChoice{
-				Type: openai.ToolTypeFunction,
-				Function: openai.ToolFunction{
-					Name: onlyOneToolName,
-				},
-			}
-		} else if len(allowedToolNames) > 1 {
+			// Some OpenAI-compatible gateways reject the object form
+			// {"type":"function","function":{"name":"..."}}
+			// with "unknown parameter: tool_choice.function", while still
+			// supporting tool calling with the string form "required".
+			//
+			// In the single-tool case, "required" is semantically equivalent
+			// to forcing that one tool, so prefer the more compatible wire form.
+			req.ToolChoice = toolChoiceRequired
+		} else if len(allowedToolNames) > 0 {
 			req.ToolChoice = map[string]any{
 				"type": "allowed_tools",
 				"allowed_tools": allowedTools{
@@ -1314,13 +1315,18 @@ func toTools(tis []*schema.ToolInfo) ([]tool, error) {
 
 		sortArrayFields(paramsJSONSchema)
 
-		tools[i] = tool{
-			Function: &functionDefinition{
-				Name:        ti.Name,
-				Description: ti.Desc,
-				Parameters:  paramsJSONSchema,
-			},
+		fd := &functionDefinition{
+			Name:        ti.Name,
+			Description: ti.Desc,
+			Parameters:  paramsJSONSchema,
+		}
+		// Support strict tool use via ToolInfo.Extra["strict"] = true.
+		// When enabled, the API guarantees that tool call inputs conform
+		// to the declared JSON Schema exactly (OpenAI strict mode).
+		if strict, ok := ti.Extra["strict"].(bool); ok && strict {
+			fd.Strict = &strict
 		}
+		tools[i] = tool{Function: fd}
 	}
 
 	return tools, nil
diff --git a/libs/acl/openai/chat_model_test.go b/libs/acl/openai/chat_model_test.go
index 098956c49..91a771a4a 100644
--- a/libs/acl/openai/chat_model_test.go
+++ b/libs/acl/openai/chat_model_test.go
@@ -373,6 +373,31 @@ func TestToTools(t *testing.T) {
 	})
 }
 
+func TestGenRequest_PreservesStrictTools(t *testing.T) {
+	c := &Client{config: &Config{Model: "test-model"}}
+
+	req, _, _, _, err := c.genRequest(t.Context(),
+		[]*schema.Message{{Role: schema.User, Content: "hello"}},
+		model.WithTools([]*schema.ToolInfo{
+			{
+				Name:  "submit_memory",
+				Desc:  "Save extracted people memory",
+				Extra: map[string]any{"strict": true},
+				ParamsOneOf: schema.NewParamsOneOfByParams(map[string]*schema.ParameterInfo{
+					"people_memory": {
+						Type:     schema.Object,
+						Required: true,
+					},
+				}),
+			},
+		}),
+	)
+
+	assert.NoError(t, err)
+	assert.Len(t, req.Tools, 1)
+	assert.True(t, req.Tools[0].Function.Strict)
+}
+
 func TestBuildMessages(t *testing.T) {
 	t.Run("buildMessageFromAssistantGenMultiContent", func(t *testing.T) {
 		t.Run("success with audio", func(t *testing.T) {
@@ -995,13 +1020,7 @@ func TestPopulateToolChoice(t *testing.T) {
 		}
 		err := populateToolChoice(req, options.ToolChoice, options.AllowedToolNames)
 		assert.NoError(t, err)
-		expected := openai.ToolChoice{
-			Type: openai.ToolTypeFunction,
-			Function: openai.ToolFunction{
-				Name: "test-tool",
-			},
-		}
-		assert.Equal(t, expected, req.ToolChoice)
+		assert.Equal(t, "required", req.ToolChoice)
 	})
 
 	t.Run("tool choice forced with multiple tools", func(t *testing.T) {
@@ -1052,14 +1071,19 @@ func TestPopulateToolChoice(t *testing.T) {
 		}
 		err := populateToolChoice(req, options.ToolChoice, options.AllowedToolNames)
 		assert.NoError(t, err)
-
-		expected := openai.ToolChoice{
-			Type: openai.ToolTypeFunction,
-			Function: openai.ToolFunction{
-				Name: "test-tool-1",
+		expected := allowedTools{
+			Mode: "required",
+			Tools: []openai.ToolChoice{
+				{
+					Type: openai.ToolTypeFunction,
+					Function: openai.ToolFunction{
+						Name: "test-tool-1",
+					},
+				},
 			},
 		}
-		assert.Equal(t, expected, req.ToolChoice)
+		assert.Equal(t, "allowed_tools", req.ToolChoice.(map[string]any)["type"])
+		assert.Equal(t, expected, req.ToolChoice.(map[string]any)["allowed_tools"])
 	})
 
 	t.Run("tool choice forced with invalid allowed tool", func(t *testing.T) {
diff --git a/libs/acl/openai/tool.go b/libs/acl/openai/tool.go
index 38b9dc9b2..58561a00c 100644
--- a/libs/acl/openai/tool.go
+++ b/libs/acl/openai/tool.go
@@ -28,4 +28,5 @@ type functionDefinition struct {
 	Name        string             `json:"name"`
 	Description string             `json:"description,omitempty"`
 	Parameters  *jsonschema.Schema `json:"parameters"`
+	Strict      *bool              `json:"strict,omitempty"`
 }