fix: add connection readiness check and retry mechanism for MCP servers

- Add connection readiness check before marking server as connected
- Implement retry logic with exponential backoff for initial tool list fetch
- Add retry mechanism for tool calls to handle connection initialization race
- Wait for server to be fully ready before showing 'Running' status

This fixes the issue where the first MCP tool call fails with 'Connection closed'
error after marketplace installation, ensuring servers are fully initialized
before accepting tool calls.

Fixes #8468

Author: roomote

src/services/mcp/McpHub.ts

@@ -831,14 +831,33 @@ export class McpHub {
 
 			// Connect (this will automatically start the transport)
 			await client.connect(transport)
-			connection.server.status = "connected"
-			connection.server.error = ""
-			connection.server.instructions = client.getInstructions()
 
-			// Initial fetch of tools and resources
-			connection.server.tools = await this.fetchToolsList(name, source)
-			connection.server.resources = await this.fetchResourcesList(name, source)
-			connection.server.resourceTemplates = await this.fetchResourceTemplatesList(name, source)
+			// Wait for the connection to be fully established before marking as connected
+			// This helps prevent "Connection closed" errors on first tool call after installation
+			try {
+				// Attempt to fetch tools list as a connection readiness check
+				// If this fails, the connection isn't ready yet
+				const tools = await this.fetchToolsListWithRetry(name, source, client)
+
+				// Connection is ready, mark as connected
+				connection.server.status = "connected"
+				connection.server.error = ""
+				connection.server.instructions = client.getInstructions()
+				connection.server.tools = tools
+
+				// Fetch remaining resources
+				connection.server.resources = await this.fetchResourcesList(name, source)
+				connection.server.resourceTemplates = await this.fetchResourceTemplatesList(name, source)
+			} catch (readinessError) {
+				// If we can't fetch tools, the connection isn't ready
+				console.error(`Server ${name} failed readiness check:`, readinessError)
+				connection.server.status = "disconnected"
+				this.appendErrorMessage(
+					connection,
+					`Connection not ready: ${readinessError instanceof Error ? readinessError.message : String(readinessError)}`,
+				)
+				throw new Error(`MCP server ${name} failed to initialize properly. Please try restarting the server.`)
+			}
 		} catch (error) {
 			// Update status with error
 			const connection = this.findConnection(name, source)
@@ -902,6 +921,90 @@ export class McpHub {
 		)
 	}
 
+	/**
+	 * Fetches the tools list with retry logic to handle connection initialization race conditions.
+	 * This is particularly important for newly installed MCP servers from the marketplace.
+	 * @param serverName The name of the server
+	 * @param source The source of the server (global or project)
+	 * @param client Optional client to use directly (for initial connection check)
+	 * @returns Promise<McpTool[]> The list of tools
+	 */
+	private async fetchToolsListWithRetry(
+		serverName: string,
+		source?: "global" | "project",
+		client?: Client,
+	): Promise<McpTool[]> {
+		const maxRetries = 3
+		const baseDelay = 500 // Start with 500ms delay
+
+		for (let attempt = 0; attempt < maxRetries; attempt++) {
+			try {
+				// If client is provided, use it directly for the request
+				if (client) {
+					const response = await client.request({ method: "tools/list" }, ListToolsResultSchema)
+
+					// If successful, fetch the full tool configuration
+					const connection = this.findConnection(serverName, source)
+					if (connection) {
+						const actualSource = connection.server.source || "global"
+						let alwaysAllowConfig: string[] = []
+						let disabledToolsList: string[] = []
+
+						try {
+							let serverConfigData: Record<string, any> = {}
+							if (actualSource === "project") {
+								const projectMcpPath = await this.getProjectMcpPath()
+								if (projectMcpPath) {
+									const content = await fs.readFile(projectMcpPath, "utf-8")
+									serverConfigData = JSON.parse(content)
+								}
+							} else {
+								const configPath = await this.getMcpSettingsFilePath()
+								const content = await fs.readFile(configPath, "utf-8")
+								serverConfigData = JSON.parse(content)
+							}
+							if (serverConfigData) {
+								alwaysAllowConfig = serverConfigData.mcpServers?.[serverName]?.alwaysAllow || []
+								disabledToolsList = serverConfigData.mcpServers?.[serverName]?.disabledTools || []
+							}
+						} catch (error) {
+							console.error(`Failed to read tool configuration for ${serverName}:`, error)
+						}
+
+						const tools = (response?.tools || []).map((tool) => ({
+							...tool,
+							alwaysAllow: alwaysAllowConfig.includes(tool.name),
+							enabledForPrompt: !disabledToolsList.includes(tool.name),
+						}))
+
+						return tools
+					}
+					return response?.tools || []
+				} else {
+					// Use the existing fetchToolsList method
+					return await this.fetchToolsList(serverName, source)
+				}
+			} catch (error) {
+				const isLastAttempt = attempt === maxRetries - 1
+
+				if (isLastAttempt) {
+					console.error(`Failed to fetch tools for ${serverName} after ${maxRetries} attempts:`, error)
+					throw error
+				}
+
+				// Calculate exponential backoff delay
+				const delay = baseDelay * Math.pow(2, attempt)
+				console.log(
+					`Retrying tools fetch for ${serverName} after ${delay}ms (attempt ${attempt + 1}/${maxRetries})`,
+				)
+				await new Promise((resolve) => setTimeout(resolve, delay))
+			}
+		}
+
+		// This should never be reached due to the throw in the last attempt
+		return []
+	}
+
 	private async fetchToolsList(serverName: string, source?: "global" | "project"): Promise<McpTool[]> {
 		try {
 			// Use the helper method to find the connection
@@ -1601,19 +1704,50 @@ export class McpHub {
 			timeout = 60 * 1000
 		}
 
-		return await connection.client.request(
-			{
-				method: "tools/call",
-				params: {
-					name: toolName,
-					arguments: toolArguments,
-				},
-			},
-			CallToolResultSchema,
-			{
-				timeout,
-			},
-		)
+		// Add retry logic for tool calls to handle connection initialization race conditions
+		// This is particularly important for the first tool call after marketplace installation
+		const maxRetries = 2
+		const retryDelay = 1000 // 1 second delay between retries
+
+		for (let attempt = 0; attempt < maxRetries; attempt++) {
+			try {
+				return await connection.client.request(
+					{
+						method: "tools/call",
+						params: {
+							name: toolName,
+							arguments: toolArguments,
+						},
+					},
+					CallToolResultSchema,
+					{
+						timeout,
+					},
+				)
+			} catch (error: any) {
+				const isLastAttempt = attempt === maxRetries - 1
+				const isConnectionError = error?.code === -32000 && error?.message?.includes("Connection closed")
+
+				// Only retry on connection errors, not on other types of errors
+				if (!isConnectionError || isLastAttempt) {
+					throw error
+				}
+
+				console.log(
+					`Tool call failed with connection error, retrying in ${retryDelay}ms (attempt ${attempt + 1}/${maxRetries})`,
+				)
+				await new Promise((resolve) => setTimeout(resolve, retryDelay))
+
+				// Check if connection is still valid before retrying
+				const retryConnection = this.findConnection(serverName, source)
+				if (!retryConnection || retryConnection.type !== "connected") {
+					throw new Error(`Connection lost for server: ${serverName}`)
+				}
+			}
+		}
+
+		// This should never be reached due to the throw in the last attempt
+		throw new Error(`Failed to call tool ${toolName} on server ${serverName} after ${maxRetries} attempts`)
 	}
 
 	/**