Add MCP loading indicator when initializing Gemini CLI (#6923)

packages/core/src/config/config.ts

@@ -54,6 +54,7 @@ import type { AnyToolInvocation } from '../tools/tools.js';
 import { WorkspaceContext } from '../utils/workspaceContext.js';
 import { Storage } from './storage.js';
 import { FileExclusions } from '../utils/ignorePatterns.js';
+import type { EventEmitter } from 'node:events';
 
 export enum ApprovalMode {
   DEFAULT = 'default',
@@ -207,6 +208,7 @@ export interface ConfigParameters {
   skipNextSpeakerCheck?: boolean;
   extensionManagement?: boolean;
   enablePromptCompletion?: boolean;
+  eventEmitter?: EventEmitter;
 }
 
 export class Config {
@@ -282,6 +284,7 @@ export class Config {
   private initialized: boolean = false;
   readonly storage: Storage;
   private readonly fileExclusions: FileExclusions;
+  private readonly eventEmitter?: EventEmitter;
 
   constructor(params: ConfigParameters) {
     this.sessionId = params.sessionId;
@@ -356,6 +359,7 @@ export class Config {
     this.storage = new Storage(this.targetDir);
     this.enablePromptCompletion = params.enablePromptCompletion ?? false;
     this.fileExclusions = new FileExclusions(this);
+    this.eventEmitter = params.eventEmitter;
 
     if (params.contextFileName) {
       setGeminiMdFilename(params.contextFileName);
@@ -803,7 +807,7 @@ export class Config {
   }
 
   async createToolRegistry(): Promise<ToolRegistry> {
-    const registry = new ToolRegistry(this);
+    const registry = new ToolRegistry(this, this.eventEmitter);
 
     // helper to create & register core tools that are enabled
     // eslint-disable-next-line @typescript-eslint/no-explicit-any

packages/core/src/tools/mcp-client-manager.ts

@@ -13,6 +13,7 @@ import {
   populateMcpServerCommand,
 } from './mcp-client.js';
 import { getErrorMessage } from '../utils/errors.js';
+import type { EventEmitter } from 'node:events';
 import type { WorkspaceContext } from '../utils/workspaceContext.js';
 
 /**
@@ -29,6 +30,7 @@ export class McpClientManager {
   private readonly debugMode: boolean;
   private readonly workspaceContext: WorkspaceContext;
   private discoveryState: MCPDiscoveryState = MCPDiscoveryState.NOT_STARTED;
+  private readonly eventEmitter?: EventEmitter;
 
   constructor(
     mcpServers: Record<string, MCPServerConfig>,
@@ -37,6 +39,7 @@ export class McpClientManager {
     promptRegistry: PromptRegistry,
     debugMode: boolean,
     workspaceContext: WorkspaceContext,
+    eventEmitter?: EventEmitter,
   ) {
     this.mcpServers = mcpServers;
     this.mcpServerCommand = mcpServerCommand;
@@ -44,6 +47,7 @@ export class McpClientManager {
     this.promptRegistry = promptRegistry;
     this.debugMode = debugMode;
     this.workspaceContext = workspaceContext;
+    this.eventEmitter = eventEmitter;
   }
 
   /**
@@ -53,14 +57,28 @@ export class McpClientManager {
    */
   async discoverAllMcpTools(): Promise<void> {
     await this.stop();
-    this.discoveryState = MCPDiscoveryState.IN_PROGRESS;
+
     const servers = populateMcpServerCommand(
       this.mcpServers,
       this.mcpServerCommand,
     );
 
-    const discoveryPromises = Object.entries(servers).map(
-      async ([name, config]) => {
+    const serverEntries = Object.entries(servers);
+    const total = serverEntries.length;
+
+    this.eventEmitter?.emit('mcp-servers-discovery-start', { count: total });
+
+    this.discoveryState = MCPDiscoveryState.IN_PROGRESS;
+
+    const discoveryPromises = serverEntries.map(
+      async ([name, config], index) => {
+        const current = index + 1;
+        this.eventEmitter?.emit('mcp-server-connecting', {
+          name,
+          current,
+          total,
+        });
+
         const client = new McpClient(
           name,
           config,
@@ -70,10 +88,22 @@ export class McpClientManager {
           this.debugMode,
         );
         this.clients.set(name, client);
+
         try {
           await client.connect();
           await client.discover();
+          this.eventEmitter?.emit('mcp-server-connected', {
+            name,
+            current,
+            total,
+          });
         } catch (error) {
+          this.eventEmitter?.emit('mcp-server-error', {
+            name,
+            current,
+            total,
+            error,
+          });
           // Log the error but don't let a single failed server stop the others
           console.error(
             `Error during discovery for server '${name}': ${getErrorMessage(

packages/core/src/tools/tool-registry.ts

@@ -20,6 +20,7 @@ import { DiscoveredMCPTool } from './mcp-tool.js';
 import { parse } from 'shell-quote';
 import { ToolErrorType } from './tool-error.js';
 import { safeJsonStringify } from '../utils/safeJsonStringify.js';
+import type { EventEmitter } from 'node:events';
 
 type ToolParams = Record<string, unknown>;
 
@@ -170,7 +171,7 @@ export class ToolRegistry {
   private config: Config;
   private mcpClientManager: McpClientManager;
 
-  constructor(config: Config) {
+  constructor(config: Config, eventEmitter?: EventEmitter) {
     this.config = config;
     this.mcpClientManager = new McpClientManager(
       this.config.getMcpServers() ?? {},
@@ -179,6 +180,7 @@ export class ToolRegistry {
       this.config.getPromptRegistry(),
       this.config.getDebugMode(),
       this.config.getWorkspaceContext(),
+      eventEmitter,
     );
   }