Replace hyphen encoding with fuzzy matching for MCP tool names (#10775)

Author: daniel-lxs

src/core/prompts/tools/native-tools/__tests__/mcp_server.spec.ts

@@ -89,7 +89,7 @@ describe("getMcpServerTools", () => {
 
 		// Should only have one tool (from project server)
 		expect(result).toHaveLength(1)
-		expect(getFunction(result[0]).name).toBe("mcp--context7--resolve___library___id")
+		expect(getFunction(result[0]).name).toBe("mcp--context7--resolve-library-id")
 		// Project server takes priority
 		expect(getFunction(result[0]).description).toBe("Project description")
 	})

src/core/tools/UseMcpToolTool.ts

@@ -4,6 +4,7 @@ import { Task } from "../task/Task"
 import { formatResponse } from "../prompts/responses"
 import { t } from "../../i18n"
 import type { ToolUse } from "../../shared/tools"
+import { toolNamesMatch } from "../../utils/mcp-name"
 
 import { BaseTool, ToolCallbacks } from "./BaseTool"
 
@@ -43,14 +44,18 @@ export class UseMcpToolTool extends BaseTool<"use_mcp_tool"> {
 				return
 			}
 
+			// Use the resolved tool name (original name from the server) for MCP calls
+			// This handles cases where models mangle hyphens to underscores
+			const resolvedToolName = toolValidation.resolvedToolName ?? toolName
+
 			// Reset mistake count on successful validation
 			task.consecutiveMistakeCount = 0
 
 			// Get user approval
 			const completeMessage = JSON.stringify({
 				type: "use_mcp_tool",
 				serverName,
-				toolName,
+				toolName: resolvedToolName,
 				arguments: params.arguments ? JSON.stringify(params.arguments) : undefined,
 			} satisfies ClineAskUseMcpServer)
 
@@ -65,7 +70,7 @@ export class UseMcpToolTool extends BaseTool<"use_mcp_tool"> {
 			await this.executeToolAndProcessResult(
 				task,
 				serverName,
-				toolName,
+				resolvedToolName,
 				parsedArguments,
 				executionId,
 				pushToolResult,
@@ -137,7 +142,7 @@ export class UseMcpToolTool extends BaseTool<"use_mcp_tool"> {
 		serverName: string,
 		toolName: string,
 		pushToolResult: (content: string) => void,
-	): Promise<{ isValid: boolean; availableTools?: string[] }> {
+	): Promise<{ isValid: boolean; availableTools?: string[]; resolvedToolName?: string }> {
 		try {
 			// Get the MCP hub to access server information
 			const provider = task.providerRef.deref()
@@ -186,8 +191,8 @@ export class UseMcpToolTool extends BaseTool<"use_mcp_tool"> {
 				return { isValid: false, availableTools: [] }
 			}
 
-			// Check if the requested tool exists
-			const tool = server.tools.find((tool) => tool.name === toolName)
+			// Check if the requested tool exists (using fuzzy matching to handle model mangling of hyphens)
+			const tool = server.tools.find((t) => toolNamesMatch(t.name, toolName))
 
 			if (!tool) {
 				// Tool not found - provide list of available tools
@@ -232,8 +237,8 @@ export class UseMcpToolTool extends BaseTool<"use_mcp_tool"> {
 				return { isValid: false, availableTools: enabledToolNames }
 			}
 
-			// Tool exists and is enabled
-			return { isValid: true, availableTools: server.tools.map((tool) => tool.name) }
+			// Tool exists and is enabled - return the original tool name for use with the MCP server
+			return { isValid: true, availableTools: server.tools.map((t) => t.name), resolvedToolName: tool.name }
 		} catch (error) {
 			// If there's an error during validation, log it but don't block the tool execution
 			// The actual tool call might still fail with a proper error

src/core/tools/__tests__/useMcpToolTool.spec.ts

@@ -577,5 +577,60 @@ describe("useMcpToolTool", () => {
 			expect(callToolMock).not.toHaveBeenCalled()
 			expect(mockAskApproval).not.toHaveBeenCalled()
 		})
+
+		it("should match tool names using fuzzy matching (hyphens vs underscores)", async () => {
+			// This tests the scenario where models mangle hyphens to underscores
+			// e.g., model sends "get_user_profile" but actual tool name is "get-user-profile"
+			mockTask.consecutiveMistakeCount = 0
+
+			const callToolMock = vi.fn().mockResolvedValue({
+				content: [{ type: "text", text: "Success" }],
+			})
+
+			const mockServers = [
+				{
+					name: "test-server",
+					tools: [{ name: "get-user-profile", description: "Gets a user profile" }],
+				},
+			]
+
+			mockProviderRef.deref.mockReturnValue({
+				getMcpHub: () => ({
+					getAllServers: vi.fn().mockReturnValue(mockServers),
+					callTool: callToolMock,
+				}),
+				postMessageToWebview: vi.fn(),
+			})
+
+			// Model sends the mangled version with underscores
+			const block: ToolUse = {
+				type: "tool_use",
+				name: "use_mcp_tool",
+				params: {
+					server_name: "test-server",
+					tool_name: "get_user_profile", // Model mangled hyphens to underscores
+					arguments: "{}",
+				},
+				partial: false,
+			}
+
+			mockAskApproval.mockResolvedValue(true)
+
+			await useMcpToolTool.handle(mockTask as Task, block as any, {
+				askApproval: mockAskApproval,
+				handleError: mockHandleError,
+				pushToolResult: mockPushToolResult,
+				removeClosingTag: mockRemoveClosingTag,
+				toolProtocol: "xml",
+			})
+
+			// Tool should be found and executed
+			expect(mockTask.consecutiveMistakeCount).toBe(0)
+			expect(mockTask.recordToolError).not.toHaveBeenCalled()
+			expect(mockTask.say).toHaveBeenCalledWith("mcp_server_request_started")
+
+			// The original tool name (with hyphens) should be passed to callTool
+			expect(callToolMock).toHaveBeenCalledWith("test-server", "get-user-profile", {})
+		})
 	})
 })

src/services/mcp/McpHub.ts

@@ -38,7 +38,7 @@ import { fileExistsAtPath } from "../../utils/fs"
 import { arePathsEqual, getWorkspacePath } from "../../utils/path"
 import { injectVariables } from "../../utils/config"
 import { safeWriteJson } from "../../utils/safeWriteJson"
-import { sanitizeMcpName } from "../../utils/mcp-name"
+import { sanitizeMcpName, toolNamesMatch } from "../../utils/mcp-name"
 
 // Discriminated union for connection states
 export type ConnectedMcpConnection = {
@@ -940,16 +940,30 @@ export class McpHub {
 	 * Find a connection by sanitized server name.
 	 * This is used when parsing MCP tool responses where the server name has been
 	 * sanitized (e.g., hyphens replaced with underscores) for API compliance.
+	 * Uses fuzzy matching to handle cases where models convert hyphens to underscores.
 	 * @param sanitizedServerName The sanitized server name from the API tool call
 	 * @returns The original server name if found, or null if no match
 	 */
 	public findServerNameBySanitizedName(sanitizedServerName: string): string | null {
+		// First, check for an exact match
 		const exactMatch = this.connections.find((conn) => conn.server.name === sanitizedServerName)
 		if (exactMatch) {
 			return exactMatch.server.name
 		}
 
-		return this.sanitizedNameRegistry.get(sanitizedServerName) ?? null
+		// Check the registry for sanitized name mapping
+		const registryMatch = this.sanitizedNameRegistry.get(sanitizedServerName)
+		if (registryMatch) {
+			return registryMatch
+		}
+
+		// Use fuzzy matching: treat hyphens and underscores as equivalent
+		const fuzzyMatch = this.connections.find((conn) => toolNamesMatch(conn.server.name, sanitizedServerName))
+		if (fuzzyMatch) {
+			return fuzzyMatch.server.name
+		}
+
+		return null
 	}
 
 	private async fetchToolsList(serverName: string, source?: "global" | "project"): Promise<McpTool[]> {