feat: reduce MCP tool call UI clutter with collapsible descriptions and path truncation

- Add collapsible description in McpToolRow when in chat context
- Truncate workspace root paths in MCP arguments for cleaner display
- Add expand/collapse toggle button with chevron icon
- Add tooltip with full description on hover
- Add new translation keys for expand/collapse actions
- Add tests for collapsible description functionality

Addresses #11155

webview-ui/src/components/chat/McpExecution.tsx

@@ -14,12 +14,35 @@ import { safeJsonParse } from "@roo/core"
 
 import { cn } from "@src/lib/utils"
 import { Button } from "@src/components/ui"
+import { useExtensionState } from "@src/context/ExtensionStateContext"
 
 import CodeBlock from "../common/CodeBlock"
 import McpToolRow from "../mcp/McpToolRow"
 
 import { Markdown } from "./Markdown"
 
+/**
+ * Truncates workspace paths in a JSON string by replacing the workspace root with "./"
+ * @param jsonString - The JSON string containing paths to truncate
+ * @param cwd - The current workspace directory (optional)
+ * @returns The JSON string with truncated paths
+ */
+function truncateWorkspacePaths(jsonString: string, cwd?: string): string {
+	if (!jsonString || !cwd) return jsonString
+
+	// Normalize the cwd to handle different path separators
+	const normalizedCwd = cwd.replace(/\\/g, "/")
+
+	// Escape special regex characters in the path
+	const escapedCwd = normalizedCwd.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")
+
+	// Create a regex that matches the workspace path (with optional trailing slash)
+	const workspacePathRegex = new RegExp(escapedCwd + "/?", "g")
+
+	// Replace workspace paths with "./"
+	return jsonString.replace(workspacePathRegex, "./")
+}
+
 interface McpExecutionProps {
 	executionId: string
 	text?: string
@@ -49,6 +72,7 @@ export const McpExecution = ({
 	alwaysAllowMcp = false,
 }: McpExecutionProps) => {
 	const { t } = useTranslation("mcp")
+	const { cwd } = useExtensionState()
 
 	// State for tracking MCP response status
 	const [status, setStatus] = useState<McpExecutionStatus | null>(null)
@@ -92,6 +116,7 @@ export const McpExecution = ({
 	}, [responseText, isResponseExpanded, tryParseJson, status])
 
 	// Only parse arguments data when complete to avoid parsing partial JSON
+	// Also apply workspace path truncation for cleaner display
 	const argumentsData = useMemo(() => {
 		if (!argumentsText) {
 			return { isJson: false, formatted: "" }
@@ -108,19 +133,22 @@ export const McpExecution = ({
 			// Try to parse, but if it fails, return as-is
 			try {
 				const parsed = JSON.parse(trimmed)
+				const formatted = JSON.stringify(parsed, null, 2)
+				// Apply path truncation to show cleaner paths
+				const truncated = truncateWorkspacePaths(formatted, cwd)
 				return {
 					isJson: true,
-					formatted: JSON.stringify(parsed, null, 2),
+					formatted: truncated,
 				}
 			} catch {
-				// JSON structure looks complete but is invalid, return as-is
-				return { isJson: false, formatted: argumentsText }
+				// JSON structure looks complete but is invalid, return as-is (but still truncate paths)
+				return { isJson: false, formatted: truncateWorkspacePaths(argumentsText, cwd) }
 			}
 		}
 
-		// For non-JSON or incomplete data, just return as-is
-		return { isJson: false, formatted: argumentsText }
-	}, [argumentsText])
+		// For non-JSON or incomplete data, just return as-is (but still truncate paths)
+		return { isJson: false, formatted: truncateWorkspacePaths(argumentsText, cwd) }
+	}, [argumentsText, cwd])
 
 	const formattedResponseText = responseData.formatted
 	const formattedArgumentsText = argumentsData.formatted

webview-ui/src/components/mcp/McpToolRow.tsx

@@ -1,9 +1,12 @@
+import { useState } from "react"
 import { VSCodeCheckbox } from "@vscode/webview-ui-toolkit/react"
+import { ChevronDown } from "lucide-react"
 
 import type { McpTool } from "@roo-code/types"
 
 import { useAppTranslation } from "@src/i18n/TranslationContext"
 import { vscode } from "@src/utils/vscode"
+import { cn } from "@src/lib/utils"
 import { StandardTooltip, ToggleSwitch } from "@/components/ui"
 
 type McpToolRowProps = {
@@ -17,6 +20,7 @@ type McpToolRowProps = {
 const McpToolRow = ({ tool, serverName, serverSource, alwaysAllowMcp, isInChatContext = false }: McpToolRowProps) => {
 	const { t } = useAppTranslation()
 	const isToolEnabled = tool.enabledForPrompt ?? true
+	const [isDescriptionExpanded, setIsDescriptionExpanded] = useState(false)
 
 	const handleAlwaysAllowChange = () => {
 		if (!serverName) return
@@ -99,10 +103,39 @@ const McpToolRow = ({ tool, serverName, serverSource, alwaysAllowMcp, isInChatCo
 			</div>
 			{tool.description && (
 				<div
-					className={`mt-1 text-xs text-vscode-descriptionForeground ${
-						isToolEnabled ? "opacity-80" : "opacity-40"
-					}`}>
-					{tool.description}
+					className={cn("mt-1 text-xs text-vscode-descriptionForeground", {
+						"opacity-80": isToolEnabled,
+						"opacity-40": !isToolEnabled,
+					})}>
+					{isInChatContext ? (
+						<div className="flex items-start gap-1">
+							<StandardTooltip
+								content={isDescriptionExpanded ? t("mcp:tool.collapse") : t("mcp:tool.expand")}>
+								<button
+									onClick={() => setIsDescriptionExpanded(!isDescriptionExpanded)}
+									className="flex items-center p-0.5 -ml-0.5 rounded hover:bg-vscode-list-hoverBackground"
+									data-testid="description-toggle">
+									<ChevronDown
+										className={cn("size-3 transition-transform duration-200", {
+											"rotate-0": isDescriptionExpanded,
+											"-rotate-90": !isDescriptionExpanded,
+										})}
+									/>
+								</button>
+							</StandardTooltip>
+							<StandardTooltip content={tool.description}>
+								<span
+									className={cn("cursor-pointer", {
+										"line-clamp-2": !isDescriptionExpanded,
+									})}
+									onClick={() => setIsDescriptionExpanded(!isDescriptionExpanded)}>
+									{tool.description}
+								</span>
+							</StandardTooltip>
+						</div>
+					) : (
+						tool.description
+					)}
 				</div>
 			)}
 			{isToolEnabled &&

webview-ui/src/components/mcp/__tests__/McpToolRow.spec.tsx

@@ -13,6 +13,8 @@ vi.mock("@src/i18n/TranslationContext", () => ({
 				"mcp:tool.parameters": "Parameters",
 				"mcp:tool.noDescription": "No description",
 				"mcp:tool.togglePromptInclusion": "Toggle prompt inclusion",
+				"mcp:tool.expand": "Expand description",
+				"mcp:tool.collapse": "Collapse description",
 			}
 			return translations[key] || key
 		},
@@ -285,4 +287,72 @@ describe("McpToolRow", () => {
 		expect(toolDescription).toHaveClass("opacity-80")
 		expect(toolDescription).not.toHaveClass("opacity-40")
 	})
+
+	describe("collapsible description in chat context", () => {
+		const toolWithLongDescription = {
+			...mockTool,
+			description:
+				"This is a very long description that should be truncated to two lines when displayed in chat context. It provides detailed information about what the tool does and how it works.",
+		}
+
+		it("shows collapsible description when isInChatContext is true", () => {
+			render(<McpToolRow tool={toolWithLongDescription} isInChatContext={true} />)
+
+			// Should have the toggle button
+			const toggleButton = screen.getByTestId("description-toggle")
+			expect(toggleButton).toBeInTheDocument()
+		})
+
+		it("does not show collapsible description when isInChatContext is false", () => {
+			render(<McpToolRow tool={toolWithLongDescription} isInChatContext={false} />)
+
+			// Should not have the toggle button
+			const toggleButton = screen.queryByTestId("description-toggle")
+			expect(toggleButton).not.toBeInTheDocument()
+		})
+
+		it("expands description when toggle button is clicked", () => {
+			render(<McpToolRow tool={toolWithLongDescription} isInChatContext={true} />)
+
+			const toggleButton = screen.getByTestId("description-toggle")
+
+			// Initially collapsed - description should have line-clamp-2 class
+			const descriptionText = screen.getByText(toolWithLongDescription.description)
+			expect(descriptionText).toHaveClass("line-clamp-2")
+
+			// Click to expand
+			fireEvent.click(toggleButton)
+
+			// After expanding - description should not have line-clamp-2 class
+			expect(descriptionText).not.toHaveClass("line-clamp-2")
+		})
+
+		it("collapses description when toggle button is clicked twice", () => {
+			render(<McpToolRow tool={toolWithLongDescription} isInChatContext={true} />)
+
+			const toggleButton = screen.getByTestId("description-toggle")
+			const descriptionText = screen.getByText(toolWithLongDescription.description)
+
+			// Click to expand
+			fireEvent.click(toggleButton)
+			expect(descriptionText).not.toHaveClass("line-clamp-2")
+
+			// Click again to collapse
+			fireEvent.click(toggleButton)
+			expect(descriptionText).toHaveClass("line-clamp-2")
+		})
+
+		it("expands description when clicking on the description text", () => {
+			render(<McpToolRow tool={toolWithLongDescription} isInChatContext={true} />)
+
+			const descriptionText = screen.getByText(toolWithLongDescription.description)
+			expect(descriptionText).toHaveClass("line-clamp-2")
+
+			// Click on the description text
+			fireEvent.click(descriptionText)
+
+			// Should expand
+			expect(descriptionText).not.toHaveClass("line-clamp-2")
+		})
+	})
 })

webview-ui/src/i18n/locales/en/mcp.json

@@ -21,7 +21,9 @@
 		"alwaysAllow": "Always allow",
 		"parameters": "Parameters",
 		"noDescription": "No description",
-		"togglePromptInclusion": "Toggle inclusion in prompt"
+		"togglePromptInclusion": "Toggle inclusion in prompt",
+		"expand": "Expand description",
+		"collapse": "Collapse description"
 	},
 	"tabs": {
 		"tools": "Tools",