chore: use default driver options for connection strings

Last change missed using default driver options for connection info
without driver options. We are bringing that back now. Also the
ensureConnected is modified to use correct connectionInfo.

Author: himanshusinghs

src/common/connectionManager.ts

@@ -2,7 +2,7 @@ import { EventEmitter } from "events";
 import type { MongoClientOptions } from "mongodb";
 import { ConnectionString } from "mongodb-connection-string-url";
 import { NodeDriverServiceProvider } from "@mongosh/service-provider-node-driver";
-import { type ConnectionInfo } from "@mongosh/arg-parser";
+import { generateConnectionInfoFromCliArgs, type ConnectionInfo } from "@mongosh/arg-parser";
 import type { DeviceId } from "../helpers/deviceId.js";
 import { type UserConfig } from "./config/userConfig.js";
 import { MongoDBError, ErrorCodes } from "./errors.js";
@@ -33,6 +33,20 @@ export interface ConnectionState {
 }
 
 const MCP_TEST_DATABASE = "#mongodb-mcp";
+
+export const defaultDriverOptions: ConnectionInfo["driverOptions"] = {
+    readConcern: {
+        level: "local",
+    },
+    readPreference: "secondaryPreferred",
+    writeConcern: {
+        w: "majority",
+    },
+    timeoutMS: 30_000,
+    proxy: { useEnvironmentVariableProxies: true },
+    applyProxyToOIDC: true,
+};
+
 export class ConnectionStateConnected implements ConnectionState {
     public tag = "connected" as const;
 
@@ -171,10 +185,15 @@ export class MCPConnectionManager extends ConnectionManager {
                 components: appNameComponents,
             });
 
-            const connectionInfo = {
-                connectionString: settings.connectionString,
-                driverOptions: settings.driverOptions ?? {},
-            };
+            const connectionInfo: ConnectionInfo = settings.driverOptions
+                ? {
+                      connectionString: settings.connectionString,
+                      driverOptions: settings.driverOptions,
+                  }
+                : generateConnectionInfoFromCliArgs({
+                      ...defaultDriverOptions,
+                      connectionSpecifier: settings.connectionString,
+                  });
 
             if (connectionInfo.driverOptions.oidc) {
                 connectionInfo.driverOptions.oidc.allowedFlows ??= ["auth-code"];

src/tools/mongodb/connect/connect.ts

@@ -68,7 +68,7 @@ export class ConnectTool extends MongoDBToolBase {
                 break;
         }
 
-        await this.connectToMongoDB(connectionString);
+        await this.session.connectToMongoDB({ connectionString });
         this.updateMetadata();
 
         return {

src/tools/mongodb/mongodbTool.ts

@@ -8,6 +8,7 @@ import { LogId } from "../../common/logger.js";
 import type { Server } from "../../server.js";
 import type { ConnectionMetadata } from "../../telemetry/types.js";
 import type { ToolCallback } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { generateConnectionInfoFromCliArgs } from "@mongosh/arg-parser";
 
 export const DbOperationArgs = {
     database: z.string().describe("Database name"),
@@ -29,7 +30,11 @@ export abstract class MongoDBToolBase extends ToolBase {
 
             if (this.config.connectionString) {
                 try {
-                    await this.connectToMongoDB(this.config.connectionString);
+                    const connectionInfo = generateConnectionInfoFromCliArgs({
+                        ...this.config,
+                        connectionSpecifier: this.config.connectionString,
+                    });
+                    await this.session.connectToMongoDB(connectionInfo);
                 } catch (error) {
                     this.session.logger.error({
                         id: LogId.mongodbConnectFailure,
@@ -108,10 +113,6 @@ export abstract class MongoDBToolBase extends ToolBase {
         return super.handleError(error, args);
     }
 
-    protected connectToMongoDB(connectionString: string): Promise<void> {
-        return this.session.connectToMongoDB({ connectionString });
-    }
-
     /**
      * Resolves the tool metadata from the arguments passed to the mongoDB tools.
      *