diff --git a/eslint.config.js b/eslint.config.js
index ec5fd5b8..6356bded 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -48,6 +48,10 @@ export default defineConfig([
         rules: {
             "@typescript-eslint/switch-exhaustiveness-check": "error",
             "@typescript-eslint/no-non-null-assertion": "error",
+            eqeqeq: "error",
+            "no-self-compare": "error",
+            "no-unassigned-vars": "error",
+            "@typescript-eslint/await-thenable": "error",
         },
     },
     globalIgnores([
diff --git a/src/common/atlas/apiClient.ts b/src/common/atlas/apiClient.ts
index 66f9ada1..6c885584 100644
--- a/src/common/atlas/apiClient.ts
+++ b/src/common/atlas/apiClient.ts
@@ -58,7 +58,7 @@ export class ApiClient {
     private isAccessTokenValid(): boolean {
         return !!(
             this.accessToken &&
-            this.accessToken.expires_at != undefined &&
+            this.accessToken.expires_at !== undefined &&
             this.accessToken.expires_at > Date.now()
         );
     }
@@ -89,6 +89,7 @@ export class ApiClient {
                 return request;
             } catch {
                 // ignore not availble tokens, API will return 401
+                return undefined;
             }
         },
     };
@@ -183,6 +184,8 @@ export class ApiClient {
             }
             return this.accessToken;
         }
+
+        return undefined;
     }
 
     public async validateAccessToken(): Promise<void> {
diff --git a/src/common/atlas/cluster.ts b/src/common/atlas/cluster.ts
index a85e2d6f..f3557890 100644
--- a/src/common/atlas/cluster.ts
+++ b/src/common/atlas/cluster.ts
@@ -51,12 +51,12 @@ export function formatCluster(cluster: ClusterDescription20240805): Cluster {
         });
 
     const instanceSize = regionConfigs[0]?.instanceSize ?? "UNKNOWN";
-    const clusterInstanceType = instanceSize == "M0" ? "FREE" : "DEDICATED";
+    const clusterInstanceType = instanceSize === "M0" ? "FREE" : "DEDICATED";
 
     return {
         name: cluster.name,
         instanceType: clusterInstanceType,
-        instanceSize: clusterInstanceType == "DEDICATED" ? instanceSize : undefined,
+        instanceSize: clusterInstanceType === "DEDICATED" ? instanceSize : undefined,
         state: cluster.stateName,
         mongoDBVersion: cluster.mongoDBVersion,
         connectionString: cluster.connectionStrings?.standardSrv || cluster.connectionStrings?.standard,
diff --git a/src/tools/atlas/connect/connectCluster.ts b/src/tools/atlas/connect/connectCluster.ts
index e83c3040..a0087a0e 100644
--- a/src/tools/atlas/connect/connectCluster.ts
+++ b/src/tools/atlas/connect/connectCluster.ts
@@ -136,8 +136,8 @@ export class ConnectClusterTool extends AtlasToolBase {
         for (let i = 0; i < 600; i++) {
             if (
                 !this.session.connectedAtlasCluster ||
-                this.session.connectedAtlasCluster.projectId != projectId ||
-                this.session.connectedAtlasCluster.clusterName != clusterName
+                this.session.connectedAtlasCluster.projectId !== projectId ||
+                this.session.connectedAtlasCluster.clusterName !== clusterName
             ) {
                 throw new Error("Cluster connection aborted");
             }
@@ -164,8 +164,8 @@ export class ConnectClusterTool extends AtlasToolBase {
 
         if (lastError) {
             if (
-                this.session.connectedAtlasCluster?.projectId == projectId &&
-                this.session.connectedAtlasCluster?.clusterName == clusterName &&
+                this.session.connectedAtlasCluster?.projectId === projectId &&
+                this.session.connectedAtlasCluster?.clusterName === clusterName &&
                 this.session.connectedAtlasCluster?.username
             ) {
                 void this.session.apiClient
diff --git a/tsconfig.build.json b/tsconfig.build.json
index 57edf983..48a9b414 100644
--- a/tsconfig.build.json
+++ b/tsconfig.build.json
@@ -14,7 +14,8 @@
     "skipLibCheck": true,
     "resolveJsonModule": true,
     "allowSyntheticDefaultImports": true,
-    "typeRoots": ["./node_modules/@types", "./src/types"]
+    "typeRoots": ["./node_modules/@types", "./src/types"],
+    "noImplicitReturns": true
   },
   "include": ["src/**/*.ts"]
 }