feat: implement MCP tool grouping and search functionality

backend/docs/docs.go

@@ -6525,6 +6525,30 @@ const docTemplate = `{
                 }
             }
         },
+        "/settings/mcp-policy": {
+            "get": {
+                "security": [
+                    {
+                        "BearerAuth": []
+                    }
+                ],
+                "produces": [
+                    "application/json"
+                ],
+                "tags": [
+                    "settings"
+                ],
+                "summary": "查询 MCP 工具运行策略",
+                "responses": {
+                    "200": {
+                        "description": "OK",
+                        "schema": {
+                            "$ref": "#/definitions/github_com_DEEIX-AI_DEEIX-Chat_backend_internal_shared_response.Envelope"
+                        }
+                    }
+                }
+            }
+        },
         "/settings/model-option-policy": {
             "get": {
                 "security": [
@@ -11713,7 +11737,7 @@ const docTemplate = `{
                 },
                 "selectedToolIDs": {
                     "type": "array",
-                    "maxItems": 32,
+                    "maxItems": 128,
                     "items": {
                         "type": "integer"
                     }

backend/docs/swagger.json

@@ -6518,6 +6518,30 @@
                 }
             }
         },
+        "/settings/mcp-policy": {
+            "get": {
+                "security": [
+                    {
+                        "BearerAuth": []
+                    }
+                ],
+                "produces": [
+                    "application/json"
+                ],
+                "tags": [
+                    "settings"
+                ],
+                "summary": "查询 MCP 工具运行策略",
+                "responses": {
+                    "200": {
+                        "description": "OK",
+                        "schema": {
+                            "$ref": "#/definitions/github_com_DEEIX-AI_DEEIX-Chat_backend_internal_shared_response.Envelope"
+                        }
+                    }
+                }
+            }
+        },
         "/settings/model-option-policy": {
             "get": {
                 "security": [
@@ -11706,7 +11730,7 @@
                 },
                 "selectedToolIDs": {
                     "type": "array",
-                    "maxItems": 32,
+                    "maxItems": 128,
                     "items": {
                         "type": "integer"
                     }

backend/docs/swagger.yaml

@@ -3278,7 +3278,7 @@ definitions:
       selectedToolIDs:
         items:
           type: integer
-        maxItems: 32
+        maxItems: 128
         type: array
       sourceMessagePublicID:
         maxLength: 32
@@ -7628,6 +7628,20 @@ paths:
       summary: 查询公开登录页配置
       tags:
       - settings
+  /settings/mcp-policy:
+    get:
+      produces:
+      - application/json
+      responses:
+        "200":
+          description: OK
+          schema:
+            $ref: '#/definitions/github_com_DEEIX-AI_DEEIX-Chat_backend_internal_shared_response.Envelope'
+      security:
+      - BearerAuth: []
+      summary: 查询 MCP 工具运行策略
+      tags:
+      - settings
   /settings/model-option-policy:
     get:
       produces:

backend/internal/application/conversation/errs.go

@@ -39,6 +39,8 @@ var (
 	ErrEmbeddingUnavailable = errors.New("embedding unavailable")
 	// ErrTooManyMessageFiles 单条消息文件数超限。
 	ErrTooManyMessageFiles = errors.New("too many message files")
+	// ErrTooManySelectedTools 单条消息选择的 MCP 工具数超限。
+	ErrTooManySelectedTools = errors.New("too many selected tools")
 	// ErrInvalidMessageBranch 消息分支参数无效。
 	ErrInvalidMessageBranch = errors.New("invalid message branch")
 	// ErrMessageNotFound 消息不存在或无权限。

backend/internal/application/conversation/service_message_send.go

@@ -150,6 +150,10 @@ func (s *Service) sendMessageInternal(
 	if len(input.FileIDs) > maxFiles {
 		return nil, ErrTooManyMessageFiles
 	}
+	// application 层保留兜底校验，保证非 HTTP 调用路径也遵守同一 MCP 工具数量策略。
+	if err := s.ValidateSelectedToolIDs(input.SelectedToolIDs); err != nil {
+		return nil, err
+	}
 
 	startedAt := time.Now()
 	runID := normalizeRunID(input.ClientRunID)

backend/internal/application/conversation/service_tool.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/DEEIX-AI/DEEIX-Chat/backend/internal/infra/config"
 	"github.com/DEEIX-AI/DEEIX-Chat/backend/internal/infra/mcp"
 )
 
@@ -59,6 +60,25 @@ func (s *Service) resolveMaxToolCallsPerRun() int {
 	return maxCalls
 }
 
+func (s *Service) resolveMaxSelectedToolsPerMessage() int {
+	maxTools := s.cfg.Snapshot().MCPMaxSelectedToolsPerMessage
+	if maxTools <= 0 {
+		maxTools = config.DefaultMCPMaxSelectedToolsPerMessage
+	}
+	if maxTools > config.MaxMCPSelectedToolsPerMessage {
+		maxTools = config.MaxMCPSelectedToolsPerMessage
+	}
+	return maxTools
+}
+
+// ValidateSelectedToolIDs 校验单次消息选择的 MCP 工具数量。
+func (s *Service) ValidateSelectedToolIDs(toolIDs []uint) error {
+	if len(toolIDs) > s.resolveMaxSelectedToolsPerMessage() {
+		return ErrTooManySelectedTools
+	}
+	return nil
+}
+
 func (s *Service) resolveMaxLLMCallsPerRun() int {
 	maxCalls := s.cfg.Snapshot().MCPMaxLLMCallsPerRun
 	if maxCalls <= 0 {

backend/internal/application/conversation/service_tool_test.go

@@ -50,3 +50,14 @@ func TestResolveMaxLLMCallsPerRunRequiresFollowUpRound(t *testing.T) {
 		t.Fatalf("expected minimum LLM calls per run to be 2, got %d", got)
 	}
 }
+
+func TestValidateSelectedToolIDsUsesRuntimeLimit(t *testing.T) {
+	service := &Service{cfg: config.NewRuntime(config.Config{MCPMaxSelectedToolsPerMessage: 2})}
+
+	if err := service.ValidateSelectedToolIDs([]uint{1, 2}); err != nil {
+		t.Fatalf("expected two selected tools to pass, got %v", err)
+	}
+	if err := service.ValidateSelectedToolIDs([]uint{1, 2, 3}); err != ErrTooManySelectedTools {
+		t.Fatalf("expected ErrTooManySelectedTools, got %v", err)
+	}
+}

backend/internal/application/settings/runtime_settings.go

@@ -332,6 +332,8 @@ func (r *RuntimeSettings) applyItem(cfg *config.Config, item domainsettings.Syst
 		cfg.MCPToolRetryCount = toInt(item.Value, cfg.MCPToolRetryCount)
 	case "mcp:mcp_max_concurrent_calls":
 		cfg.MCPMaxConcurrentCalls = toInt(item.Value, cfg.MCPMaxConcurrentCalls)
+	case "mcp:mcp_max_selected_tools_per_message":
+		cfg.MCPMaxSelectedToolsPerMessage = toInt(item.Value, cfg.MCPMaxSelectedToolsPerMessage)
 	case "mcp:mcp_max_llm_calls_per_run":
 		cfg.MCPMaxLLMCallsPerRun = toInt(item.Value, cfg.MCPMaxLLMCallsPerRun)
 	case "mcp:mcp_max_tool_calls_per_run":
@@ -372,6 +374,12 @@ func (r *RuntimeSettings) normalizeConfig(cfg *config.Config) {
 	if strings.TrimSpace(cfg.NativeToolAllowedTypes) == "" {
 		cfg.NativeToolAllowedTypes = config.DefaultNativeToolAllowedTypesJSON()
 	}
+	if cfg.MCPMaxSelectedToolsPerMessage <= 0 {
+		cfg.MCPMaxSelectedToolsPerMessage = config.DefaultMCPMaxSelectedToolsPerMessage
+	}
+	if cfg.MCPMaxSelectedToolsPerMessage > config.MaxMCPSelectedToolsPerMessage {
+		cfg.MCPMaxSelectedToolsPerMessage = config.MaxMCPSelectedToolsPerMessage
+	}
 	if !cfg.FileFullContextLimitEnabled {
 		cfg.FileFullContextMaxBytes = 0
 		cfg.FileFullContextMaxTokens = 0

backend/internal/application/settings/seed.go

@@ -164,6 +164,7 @@ func defaultSettings() []domainsettings.SystemSetting {
 		{Namespace: "mcp", Key: "mcp_tool_timeout_seconds", Value: "10", ValueType: "int", Description: "MCP Tool Call 超时(秒)"},
 		{Namespace: "mcp", Key: "mcp_tool_retry_count", Value: "0", ValueType: "int", Description: "MCP Tool Call 重试次数"},
 		{Namespace: "mcp", Key: "mcp_max_concurrent_calls", Value: "8", ValueType: "int", Description: "MCP Tool Call 并发上限"},
+		{Namespace: "mcp", Key: "mcp_max_selected_tools_per_message", Value: "32", ValueType: "int", Description: "单次消息最多可选择的 MCP 工具数量"},
 		{Namespace: "mcp", Key: "mcp_max_llm_calls_per_run", Value: "5", ValueType: "int", Description: "单次 MCP 工具运行最大 LLM 请求次数（最小 2，首次请求 + 工具后续请求 + 最终总结）"},
 		{Namespace: "mcp", Key: "mcp_max_tool_calls_per_run", Value: "8", ValueType: "int", Description: "单次 MCP 工具运行最大 MCP Tool Call 次数"},
 

backend/internal/application/settings/service.go

@@ -390,6 +390,8 @@ func validatePatchItem(item PatchItem) error {
 		return validateIntMinMax(value, 1, 64, key)
 	case "mcp:mcp_max_concurrent_calls":
 		return validateIntMinMax(value, 1, 64, key)
+	case "mcp:mcp_max_selected_tools_per_message":
+		return validateIntMinMax(value, 1, config.MaxMCPSelectedToolsPerMessage, key)
 	case "mcp:mcp_tool_timeout_seconds":
 		return validateIntMinMax(value, 1, 120, key)
 	case "mcp:mcp_tool_retry_count":

backend/internal/application/settings/service_test.go

@@ -135,6 +135,18 @@ func TestValidateModelOptionPolicySettings(t *testing.T) {
 	}
 }
 
+func TestValidateMCPSelectedToolsSetting(t *testing.T) {
+	if err := validatePatchItem(PatchItem{Namespace: "mcp", Key: "mcp_max_selected_tools_per_message", Value: "32"}); err != nil {
+		t.Fatalf("expected selected tool limit to pass, got %v", err)
+	}
+	if err := validatePatchItem(PatchItem{Namespace: "mcp", Key: "mcp_max_selected_tools_per_message", Value: "0"}); err == nil {
+		t.Fatal("expected zero selected tool limit to fail")
+	}
+	if err := validatePatchItem(PatchItem{Namespace: "mcp", Key: "mcp_max_selected_tools_per_message", Value: "129"}); err == nil {
+		t.Fatal("expected selected tool limit above safe maximum to fail")
+	}
+}
+
 func TestValidateFullContextLimitsAllowUnlimitedValues(t *testing.T) {
 	cases := []PatchItem{
 		{Namespace: "file", Key: "full_context_limit_enabled", Value: "true"},

backend/internal/infra/config/config.go

@@ -25,6 +25,13 @@ const (
 	defaultHTTPMaxHeaderBytes           = 1 << 20
 )
 
+const (
+	// DefaultMCPMaxSelectedToolsPerMessage 是单次消息可选择 MCP 工具数量的默认值。
+	DefaultMCPMaxSelectedToolsPerMessage = 32
+	// MaxMCPSelectedToolsPerMessage 是运行时配置允许的安全上限，防止一次请求暴露过多工具 schema。
+	MaxMCPSelectedToolsPerMessage = 128
+)
+
 // DefaultModelOptionAllowedPathsJSON 返回用户可透传模型参数的默认白名单。
 func DefaultModelOptionAllowedPathsJSON() string {
 	return `{
@@ -433,12 +440,13 @@ type Config struct {
 	ProcessTracePersistInflight    bool // 是否在流式阶段持久化轨迹
 	ContextArtifactRetentionDays   int  // 上下文证据保留天数，<=0 表示不自动过期
 	// MCP 配置
-	MCPEnable             bool
-	MCPToolTimeoutSeconds int
-	MCPToolRetryCount     int
-	MCPMaxConcurrentCalls int
-	MCPMaxLLMCallsPerRun  int
-	MCPMaxToolCallsPerRun int
+	MCPEnable                     bool
+	MCPToolTimeoutSeconds         int
+	MCPToolRetryCount             int
+	MCPMaxConcurrentCalls         int
+	MCPMaxSelectedToolsPerMessage int
+	MCPMaxLLMCallsPerRun          int
+	MCPMaxToolCallsPerRun         int
 }
 
 // defaultYAMLPaths 固定读取仓库根目录的 config.yaml。
@@ -623,6 +631,7 @@ func Load() Config {
 		MCPToolTimeoutSeconds:             10,
 		MCPToolRetryCount:                 0,
 		MCPMaxConcurrentCalls:             8,
+		MCPMaxSelectedToolsPerMessage:     DefaultMCPMaxSelectedToolsPerMessage,
 		MCPMaxLLMCallsPerRun:              5,
 		MCPMaxToolCallsPerRun:             8,
 	}

backend/internal/shared/response/error_code.go

@@ -144,6 +144,7 @@ var exactErrorSpecs = map[string]errorSpec{
 	"invalid message branch":                                  {Code: "message.invalid_branch", Message: "invalid message branch"},
 	"message generation canceled":                             {Code: "conversation_run.canceled", Message: "message generation canceled"},
 	"too many files in one message":                           {Code: "message.too_many_files", Message: "too many files in one message"},
+	"too many selected tools":                                 {Code: "message.too_many_selected_tools", Message: "too many selected tools"},
 	"generation stream not found":                             {Code: "conversation_run.stream_not_found", Message: "generation stream not found"},
 	"image prompt is required":                                {Code: "media.image_prompt_required", Message: "image prompt is required"},
 	"image generation does not accept input images":           {Code: "media.image_generation_rejects_inputs", Message: "image generation does not accept input images"},

backend/internal/transport/http/conversation/dto_request.go

@@ -84,7 +84,7 @@ type SendMessageRequest struct {
 	Options               map[string]interface{} `json:"options"`
 	ClientRunID           string                 `json:"clientRunID" binding:"omitempty,max=64"`
 	FileIDs               []string               `json:"fileIDs" binding:"max=20"`
-	SelectedToolIDs       []uint                 `json:"selectedToolIDs" binding:"max=32"`
+	SelectedToolIDs       []uint                 `json:"selectedToolIDs" binding:"max=128"`
 	ParentMessagePublicID string                 `json:"parentMessagePublicID" binding:"omitempty,max=32"`
 	SourceMessagePublicID string                 `json:"sourceMessagePublicID" binding:"omitempty,max=32"`
 	BranchReason          string                 `json:"branchReason" binding:"omitempty,oneof=default retry edit"`

backend/internal/transport/http/conversation/handler.go

@@ -111,6 +111,9 @@ func mapStreamError(err error) streamError {
 	case errors.Is(err, appconversation.ErrTooManyMessageFiles):
 		status = http.StatusBadRequest
 		message = "too many files in one message"
+	case errors.Is(err, appconversation.ErrTooManySelectedTools):
+		status = http.StatusBadRequest
+		message = "too many selected tools"
 	case errors.Is(err, appconversation.ErrFileProcessingNotReady):
 		status = http.StatusBadRequest
 		message = "file processing not ready"

backend/internal/transport/http/conversation/handler_message_send.go

@@ -66,6 +66,11 @@ func (h *Handler) parseSendMessageInput(c *gin.Context) (appconversation.SendMes
 	}
 	req.ClientRunID = appconversation.EnsureMessageGenerationRunID(req.ClientRunID)
 	req.Options = sanitizeMessageOptions(req.Options)
+	// 流式接口写入响应头前先拦截明显超限请求，避免后续只能用 NDJSON error 表达 400。
+	if err = h.service.ValidateSelectedToolIDs(req.SelectedToolIDs); err != nil {
+		handleSendMessageError(c, err)
+		return appconversation.SendMessageInput{}, nil, nil, err
+	}
 
 	conversation, err := h.service.GetConversationByPublicID(c.Request.Context(), userID, publicID)
 	if err != nil {
@@ -237,6 +242,8 @@ func handleSendMessageError(c *gin.Context, err error) {
 		response.Error(c, http.StatusBadRequest, "invalid file reference")
 	case errors.Is(err, appconversation.ErrTooManyMessageFiles):
 		response.Error(c, http.StatusBadRequest, "too many files in one message")
+	case errors.Is(err, appconversation.ErrTooManySelectedTools):
+		response.Error(c, http.StatusBadRequest, "too many selected tools")
 	case errors.Is(err, appconversation.ErrInvalidMessageBranch):
 		response.Error(c, http.StatusBadRequest, "invalid message branch")
 	case errors.Is(err, appconversation.ErrFileProcessingNotReady):

backend/internal/transport/http/settings/dto.go

@@ -45,6 +45,11 @@ type ModelOptionPolicyResponse struct {
 	NativeToolAllowedTypesJSON string `json:"nativeToolAllowedTypesJSON"`
 }
 
+// MCPPolicyResponse 返回聊天侧需要遵守的 MCP 工具运行策略。
+type MCPPolicyResponse struct {
+	MaxSelectedToolsPerMessage int `json:"maxSelectedToolsPerMessage"`
+}
+
 // ── mapping 函数 ─────────────────────────────────────────────────────────────
 
 func toAppPatchItems(items []PatchItem) []appsettings.PatchItem {

backend/internal/transport/http/settings/handler.go

@@ -155,6 +155,25 @@ func (h *Handler) GetModelOptionPolicy(c *gin.Context) {
 	})
 }
 
+// GetMCPPolicy godoc
+// @Summary 查询 MCP 工具运行策略
+// @Tags settings
+// @Produce json
+// @Security BearerAuth
+// @Success 200 {object} response.Envelope
+// @Router /settings/mcp-policy [get]
+func (h *Handler) GetMCPPolicy(c *gin.Context) {
+	cfg := h.runtime.Snapshot()
+	limit := cfg.MCPMaxSelectedToolsPerMessage
+	if limit <= 0 {
+		limit = config.DefaultMCPMaxSelectedToolsPerMessage
+	}
+	if limit > config.MaxMCPSelectedToolsPerMessage {
+		limit = config.MaxMCPSelectedToolsPerMessage
+	}
+	response.Success(c, MCPPolicyResponse{MaxSelectedToolsPerMessage: limit})
+}
+
 // Patch godoc
 // @Summary 批量更新配置项
 // @Description 批量更新动态配置并清除缓存，下次读取自动刷新

backend/internal/transport/http/settings/router.go

@@ -8,6 +8,7 @@ func (m *Module) RegisterPublicRoutes(api *gin.RouterGroup) {
 
 func (m *Module) RegisterRoutes(api *gin.RouterGroup) {
 	api.GET("/settings/model-option-policy", m.Handler.GetModelOptionPolicy)
+	api.GET("/settings/mcp-policy", m.Handler.GetMCPPolicy)
 }
 
 // RegisterAdminRoutes 注册 settings 管理路由（由管理员中间件保护）。