From 29943127141f99eca763a850d7bb5e013bb497f7 Mon Sep 17 00:00:00 2001
From: Hongda Chen <54146249+Adancurusul@users.noreply.github.com>
Date: Fri, 29 Aug 2025 16:18:27 +0800
Subject: [PATCH] fix: MCP client global variable causes tool duplication

Replace global mcpClient with Map to store separate client instances
for each MCP server. Previously all servers shared one client and
showed identical tools.
---
 packages/core/src/tools/mcp-client.ts | 34 ++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/packages/core/src/tools/mcp-client.ts b/packages/core/src/tools/mcp-client.ts
index 00d7dc41..aa195c52 100644
--- a/packages/core/src/tools/mcp-client.ts
+++ b/packages/core/src/tools/mcp-client.ts
@@ -53,7 +53,8 @@ const mcpServerStatusesInternal: Map<string, MCPServerStatus> = new Map();
  */
 let mcpDiscoveryState: MCPDiscoveryState = MCPDiscoveryState.NOT_STARTED;
 
-let mcpClient: Client | null = null;
+// Store all active MCP client connections
+const mcpClients: Map<string, Client> = new Map();
 
 /**
  * Event listeners for MCP server status changes
@@ -213,11 +214,15 @@ async function connectAndDiscover(
     return;
   }
 
-  mcpClient = new Client({
+  // Create a new client instance for each MCP server
+  const mcpClient = new Client({
     name: 'gemini-cli-mcp-client',
     version: '0.0.1',
   });
 
+  // Store the client for later cleanup
+  mcpClients.set(mcpServerName, mcpClient);
+
   // patch Client.callTool to use request timeout as genai McpCallTool.callTool does not do it
   // TODO: remove this hack once GenAI SDK does callTool with request options
   if ('callTool' in mcpClient) {
@@ -255,15 +260,17 @@ async function connectAndDiscover(
       errorString += `\nMake sure it is available in the sandbox`;
     }
     console.error(errorString);
-    // Update status to disconnected
+    // Update status to disconnected and cleanup
     updateMCPServerStatus(mcpServerName, MCPServerStatus.DISCONNECTED);
+    mcpClients.delete(mcpServerName);
     return;
   }
 
   mcpClient.onerror = (error) => {
     console.error(`MCP ERROR (${mcpServerName}):`, error.toString());
-    // Update status to disconnected on error
+    // Update status to disconnected on error and cleanup
     updateMCPServerStatus(mcpServerName, MCPServerStatus.DISCONNECTED);
+    mcpClients.delete(mcpServerName);
   };
 
   if (transport instanceof StdioClientTransport && transport.stderr) {
@@ -291,8 +298,9 @@ async function connectAndDiscover(
       ) {
         await transport.close();
       }
-      // Update status to disconnected
+      // Update status to disconnected and cleanup
       updateMCPServerStatus(mcpServerName, MCPServerStatus.DISCONNECTED);
+      mcpClients.delete(mcpServerName);
       return;
     }
 
@@ -368,8 +376,9 @@ async function connectAndDiscover(
     ) {
       await transport.close();
     }
-    // Update status to disconnected
+    // Update status to disconnected and cleanup
     updateMCPServerStatus(mcpServerName, MCPServerStatus.DISCONNECTED);
+    mcpClients.delete(mcpServerName);
   }
 
   // If no tools were registered from this MCP server, the following 'if' block
@@ -387,8 +396,9 @@ async function connectAndDiscover(
       transport instanceof StreamableHTTPClientTransport
     ) {
       await transport.close();
-      // Update status to disconnected
+      // Update status to disconnected and cleanup
       updateMCPServerStatus(mcpServerName, MCPServerStatus.DISCONNECTED);
+      mcpClients.delete(mcpServerName);
     }
   }
 }
@@ -397,7 +407,13 @@ async function connectAndDiscover(
  * Close all MCP connections.
  */
 export async function closeAllMCPConnections() {
-  if (mcpClient) {
-    await mcpClient.close();
+  // Close all stored MCP client connections
+  for (const [serverName, client] of mcpClients.entries()) {
+    try {
+      await client.close();
+      mcpClients.delete(serverName);
+    } catch (error) {
+      console.error(`Error closing MCP client for ${serverName}:`, error);
+    }
   }
 }