diff --git a/src/vs/editor/common/languages.ts b/src/vs/editor/common/languages.ts
index 566872323a3..126f4bf6335 100644
--- a/src/vs/editor/common/languages.ts
+++ b/src/vs/editor/common/languages.ts
@@ -1765,6 +1765,7 @@ export enum InlayHintKind {
 
 export interface InlayHintLabelPart {
 	label: string;
+	tooltip?: string | IMarkdownString
 	// collapsible?: boolean;
 	command?: Command
 	location?: Location;
diff --git a/src/vs/editor/contrib/inlayHints/inlayHintsHover.ts b/src/vs/editor/contrib/inlayHints/inlayHintsHover.ts
index 578f37c42db..102c8de52a5 100644
--- a/src/vs/editor/contrib/inlayHints/inlayHintsHover.ts
+++ b/src/vs/editor/contrib/inlayHints/inlayHintsHover.ts
@@ -72,17 +72,28 @@ export class InlayHintsHover extends MarkdownHoverParticipant implements IEditor
 			}
 
 			// (1) Inlay Tooltip
-			let contents: IMarkdownString | undefined;
+			let itemTooltip: IMarkdownString | undefined;
 			if (typeof part.item.hint.tooltip === 'string') {
-				contents = new MarkdownString().appendText(part.item.hint.tooltip);
+				itemTooltip = new MarkdownString().appendText(part.item.hint.tooltip);
 			} else if (part.item.hint.tooltip) {
-				contents = part.item.hint.tooltip;
+				itemTooltip = part.item.hint.tooltip;
 			}
-			if (contents) {
-				executor.emitOne(new MarkdownHover(this, anchor.range, [contents], 0));
+			if (itemTooltip) {
+				executor.emitOne(new MarkdownHover(this, anchor.range, [itemTooltip], 0));
 			}
 
 			// (2) Inlay Label Part Tooltip
+			let partTooltip: IMarkdownString | undefined;
+			if (typeof part.part.tooltip === 'string') {
+				partTooltip = new MarkdownString().appendText(part.part.tooltip);
+			} else if (part.part.tooltip) {
+				partTooltip = part.part.tooltip;
+			}
+			if (partTooltip) {
+				executor.emitOne(new MarkdownHover(this, anchor.range, [partTooltip], 1));
+			}
+
+			// (3) Inlay Label Part Location tooltip
 			const iterable = await this._resolveInlayHintLabelPartHover(part, token);
 			for await (let item of iterable) {
 				executor.emitOne(item);
@@ -91,9 +102,6 @@ export class InlayHintsHover extends MarkdownHoverParticipant implements IEditor
 	}
 
 	private async _resolveInlayHintLabelPartHover(part: RenderedInlayHintLabelPart, token: CancellationToken): Promise<AsyncIterableObject<MarkdownHover>> {
-		if (typeof part.item.hint.label === 'string') {
-			return AsyncIterableObject.EMPTY;
-		}
 		if (!part.part.location) {
 			return AsyncIterableObject.EMPTY;
 		}
@@ -106,7 +114,7 @@ export class InlayHintsHover extends MarkdownHoverParticipant implements IEditor
 			}
 			return getHover(model, new Position(range.startLineNumber, range.startColumn), token)
 				.filter(item => !isEmptyMarkdownString(item.hover.contents))
-				.map(item => new MarkdownHover(this, part.item.anchor.range, item.hover.contents, item.ordinal));
+				.map(item => new MarkdownHover(this, part.item.anchor.range, item.hover.contents, 2 + item.ordinal));
 		} finally {
 			ref.dispose();
 		}
diff --git a/src/vs/monaco.d.ts b/src/vs/monaco.d.ts
index f8b02befc18..d71d3de3749 100644
--- a/src/vs/monaco.d.ts
+++ b/src/vs/monaco.d.ts
@@ -6864,6 +6864,7 @@ declare namespace monaco.languages {
 
 	export interface InlayHintLabelPart {
 		label: string;
+		tooltip?: string | IMarkdownString;
 		command?: Command;
 		location?: Location;
 	}
diff --git a/src/vs/workbench/api/common/extHostLanguageFeatures.ts b/src/vs/workbench/api/common/extHostLanguageFeatures.ts
index 22180d832a7..3b240c5d356 100644
--- a/src/vs/workbench/api/common/extHostLanguageFeatures.ts
+++ b/src/vs/workbench/api/common/extHostLanguageFeatures.ts
@@ -1268,13 +1268,14 @@ class InlayHintsAdapter {
 			result.label = hint.label;
 		} else {
 			result.label = hint.label.map(part => {
-				let r: modes.InlayHintLabelPart = { label: part.label };
+				let result: modes.InlayHintLabelPart = { label: part.label };
+				result.tooltip = part.tooltip && typeConvert.MarkdownString.from(part.tooltip);
 				if (Location.isLocation(part.location)) {
-					r.location = typeConvert.location.from(part.location);
+					result.location = typeConvert.location.from(part.location);
 				} else if (part.command) {
-					r.command = this._commands.toInternal(part.command, disposables);
+					result.command = this._commands.toInternal(part.command, disposables);
 				}
-				return r;
+				return result;
 			});
 		}
 		return result;
diff --git a/src/vs/workbench/api/common/extHostTypeConverters.ts b/src/vs/workbench/api/common/extHostTypeConverters.ts
index 6a5e23cb24e..78e3da57764 100644
--- a/src/vs/workbench/api/common/extHostTypeConverters.ts
+++ b/src/vs/workbench/api/common/extHostTypeConverters.ts
@@ -1169,7 +1169,9 @@ export namespace InlayHintLabelPart {
 
 	export function to(converter: CommandsConverter, part: modes.InlayHintLabelPart): types.InlayHintLabelPart {
 		const result = new types.InlayHintLabelPart(part.label);
-
+		result.tooltip = htmlContent.isMarkdownString(part.tooltip)
+			? MarkdownString.to(part.tooltip)
+			: part.tooltip;
 		if (modes.Command.is(part.command)) {
 			result.command = converter.fromInternal(part.command);
 		} else if (part.location) {
diff --git a/src/vs/workbench/api/common/extHostTypes.ts b/src/vs/workbench/api/common/extHostTypes.ts
index b29442ff192..c204ba85776 100644
--- a/src/vs/workbench/api/common/extHostTypes.ts
+++ b/src/vs/workbench/api/common/extHostTypes.ts
@@ -1423,7 +1423,9 @@ export enum InlayHintKind {
 
 @es5ClassCompat
 export class InlayHintLabelPart {
+
 	label: string;
+	tooltip?: string | vscode.MarkdownString;
 	location?: Location;
 	command?: vscode.Command;
 
diff --git a/src/vscode-dts/vscode.proposed.inlayHints.d.ts b/src/vscode-dts/vscode.proposed.inlayHints.d.ts
index fd0b0ab4a34..8510c247135 100644
--- a/src/vscode-dts/vscode.proposed.inlayHints.d.ts
+++ b/src/vscode-dts/vscode.proposed.inlayHints.d.ts
@@ -39,12 +39,20 @@ declare module 'vscode' {
 
 	export class InlayHintLabelPart {
 
+		/**
+		 * The value of this label part.
+		 */
 		label: string;
 
-		// invokes provider
-		location?: Location;
+		/**
+		 * The tooltip text when you hover over this label part.
+		 */
+		tooltip?: string | MarkdownString | undefined;
 
-		command?: Command;
+		// invokes provider
+		location?: Location | undefined;
+
+		command?: Command | undefined;
 
 		// todo@api
 		// context menu, contextMenuCommands