diff --git a/src/config.ts b/src/config.ts
index 0357101c..63bba69d 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -8,10 +8,11 @@ const { localDataPath, configPath } = getLocalDataPath();
 
 // If we decide to support non-string config options, we'll need to extend the mechanism for parsing
 // env variables.
-interface UserConfig extends Record<string, string> {
+interface UserConfig extends Record<string, string | undefined> {
     apiBaseUrl: string;
     clientId: string;
     stateFile: string;
+    connectionString?: string;
 }
 
 const defaults: UserConfig = {
diff --git a/src/tools/mongodb/connect.ts b/src/tools/mongodb/connect.ts
index f95cde27..6055311b 100644
--- a/src/tools/mongodb/connect.ts
+++ b/src/tools/mongodb/connect.ts
@@ -4,6 +4,7 @@ import { NodeDriverServiceProvider } from "@mongosh/service-provider-node-driver
 import { DbOperationType, MongoDBToolBase } from "./mongodbTool.js";
 import { ToolArgs } from "../tool.js";
 import { ErrorCodes, MongoDBError } from "../../errors.js";
+import config from "../../config.js";
 
 export class ConnectTool extends MongoDBToolBase {
     protected name = "connect";
@@ -20,7 +21,7 @@ export class ConnectTool extends MongoDBToolBase {
     protected async execute({
         connectionStringOrClusterName,
     }: ToolArgs<typeof this.argsShape>): Promise<CallToolResult> {
-        connectionStringOrClusterName ??= this.state.credentials.connectionString;
+        connectionStringOrClusterName ??= config.connectionString || this.state.credentials.connectionString;
         if (!connectionStringOrClusterName) {
             return {
                 content: [