diff --git a/src/vs/workbench/parts/extensions/electron-browser/extensionEditor.ts b/src/vs/workbench/parts/extensions/electron-browser/extensionEditor.ts
index e660d92bf4cd408878563aa159668febfa800e23..14f0d4d1c89f97b82cce80ac5d62efd5e92e5681 100644
--- a/src/vs/workbench/parts/extensions/electron-browser/extensionEditor.ts
+++ b/src/vs/workbench/parts/extensions/electron-browser/extensionEditor.ts
@@ -99,10 +99,12 @@ class NavBar {
 		this.actionbar = new ActionBar(element, { animated: false });
 	}
 
-	push(id: string, label: string): void {
+	push(id: string, label: string, tooltip: string): void {
 		const run = () => this._update(id);
 		const action = new Action(id, label, null, true, run);
 
+		action.tooltip = tooltip;
+
 		this.actions.push(action);
 		this.actionbar.push(action);
 
@@ -371,10 +373,10 @@ export class ExtensionEditor extends BaseEditor {
 
 		this.navbar.clear();
 		this.navbar.onChange(this.onNavbarChange.bind(this, extension), this, this.transientDisposables);
-		this.navbar.push(NavbarSection.Readme, localize('details', "Details"));
-		this.navbar.push(NavbarSection.Contributions, localize('contributions', "Contributions"));
-		this.navbar.push(NavbarSection.Changelog, localize('changelog', "Changelog"));
-		this.navbar.push(NavbarSection.Dependencies, localize('dependencies', "Dependencies"));
+		this.navbar.push(NavbarSection.Readme, localize('details', "Details"), localize('detailstooltip', "Extension details, rendered from the extension's 'README.md' file"));
+		this.navbar.push(NavbarSection.Contributions, localize('contributions', "Contributions"), localize('contributionstooltip', "Extension contributions to the VS Code editor"));
+		this.navbar.push(NavbarSection.Changelog, localize('changelog', "Changelog"), localize('changelogtooltip', "Extension update history, rendered from the extension's 'CHANGELOG.md' file"));
+		this.navbar.push(NavbarSection.Dependencies, localize('dependencies', "Dependencies"), localize('dependenciestooltip', "Extension dependencies, lists other extensions this extension depends on"));
 
 		this.editorLoadComplete = true;
 		return super.setInput(input, options);