@@ -9,6 +9,7 @@ import {
   permissionsMockFns,
   resetDbChainMock,
 } from '@sim/testing'
+import { createRouteContext } from '@sim/testing/helpers/http'
 import { NextRequest } from 'next/server'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
@@ -61,7 +62,7 @@ describe('MCP OAuth start route', () => {
       'http://localhost:3000/api/mcp/oauth/start?workspaceId=workspace-1&serverId=server-1'
     )
 
-    await GET(request)
+    await GET(request, createRouteContext({}))
 
     // The route must call the guarded wrapper (which defaults fetchFn to the
     // SSRF-guarded fetch internally) rather than the raw SDK `auth()` — see
@@ -82,7 +83,7 @@ describe('MCP OAuth start route', () => {
       'http://localhost:3000/api/mcp/oauth/start?workspaceId=workspace-1&serverId=server-1'
     )
 
-    const response = await GET(request)
+    const response = await GET(request, createRouteContext({}))
 
     expect(mcpOauthMockFns.mockMcpAuthGuarded).toHaveBeenCalledTimes(1)
     expect(response.status).toBe(504)
@@ -105,7 +106,7 @@ describe('MCP OAuth start route', () => {
       'http://localhost:3000/api/mcp/oauth/start?workspaceId=workspace-1&serverId=server-1'
     )
 
-    const response = await GET(request)
+    const response = await GET(request, createRouteContext({}))
     const body = await response.json()
 
     expect(response.status).toBe(409)
@@ -121,7 +122,7 @@ describe('MCP OAuth start route', () => {
       'http://localhost:3000/api/mcp/oauth/start?workspaceId=workspace-1&serverId=server-1'
     )
 
-    const response = await GET(request)
+    const response = await GET(request, createRouteContext({}))
     const body = await response.json()
 
     expect(response.status).toBe(500)
@@ -138,7 +139,7 @@ describe('MCP OAuth start route', () => {
       'http://localhost:3000/api/mcp/oauth/start?workspaceId=workspace-1&serverId=server-1'
     )
 
-    const response = await GET(request)
+    const response = await GET(request, createRouteContext({}))
     const body = await response.json()
 
     expect(response.status).toBe(422)
@@ -200,7 +201,8 @@ describe('MCP OAuth start route: authorization-server refusals', () => {
     GET(
       new NextRequest(
         'http://localhost:3000/api/mcp/oauth/start?workspaceId=workspace-1&serverId=server-1'
-      )
+      ),
+      createRouteContext({})
     )
 
   it.each([
 
@@ -24,6 +24,8 @@ vi.mock('@/lib/mcp/middleware', () => ({
 
 vi.mock('@/lib/mcp/service', () => mcpServiceMock)
 
+import { StreamableHTTPError } from '@modelcontextprotocol/sdk/client/streamableHttp.js'
+import { ErrorCode, McpError } from '@modelcontextprotocol/sdk/types.js'
 import { McpOauthRedirectRequired } from '@/lib/mcp/oauth'
 import { McpConnectionError, McpServerCooldownError } from '@/lib/mcp/types'
 import { GET } from '@/app/api/mcp/tools/discover/route'
@@ -56,6 +58,11 @@ describe('GET /api/mcp/tools/discover', () => {
   it.each([
     ['cannot be reached', () => new McpConnectionError('connect ECONNREFUSED', 'Docs')],
     ['is cooling down after a recent failure', () => new McpServerCooldownError('mcp-1')],
+    ['times out on tools/list', () => new McpError(ErrorCode.RequestTimeout, 'Request timed out')],
+    [
+      'answers tools/list with an HTTP error',
+      () => new StreamableHTTPError(503, 'Service Unavailable'),
+    ],
   ])('answers 422 when the registered server %s', async (_name, makeError) => {
     mcpServiceMockFns.mockDiscoverServerTools.mockRejectedValueOnce(makeError())
 
 
@@ -12,12 +12,13 @@ import {
 } from '@/lib/mcp/middleware'
 import { McpOauthRedirectRequired } from '@/lib/mcp/oauth'
 import { mcpService } from '@/lib/mcp/service'
+import { McpOauthAuthorizationRequiredError, type McpToolDiscoveryResponse } from '@/lib/mcp/types'
 import {
-  McpConnectionError,
-  McpOauthAuthorizationRequiredError,
-  type McpToolDiscoveryResponse,
-} from '@/lib/mcp/types'
-import { categorizeError, createMcpErrorResponse, createMcpSuccessResponse } from '@/lib/mcp/utils'
+  categorizeError,
+  createMcpErrorResponse,
+  createMcpSuccessResponse,
+  isMcpServerUnavailableError,
+} from '@/lib/mcp/utils'
 
 const logger = createLogger('McpToolDiscoveryAPI')
 const MCP_REFRESH_DISCOVERY_CONCURRENCY = 5
@@ -28,26 +29,30 @@ export const dynamic = 'force-dynamic'
  * Renders a discovery failure that is not an authorization problem.
  *
  * Discovery talks to a server the workspace registered, so a server that cannot be
- * reached, times out, or is cooling down after a recent failure is a fault of that
- * server rather than of Sim: it answers 422 (the request was valid; the dependency it
- * names cannot serve it), the status this API family already uses for an upstream that
- * cannot complete the operation, and logs at warn. Anything else keeps
- * {@link categorizeError}'s status and logs at error only when that status is a 5xx.
+ * reached, times out on connect or on `tools/list`, answers with a protocol or HTTP
+ * error, or is cooling down after a recent failure is a fault of that server rather
+ * than of Sim: it answers 422 (the request was valid; the dependency it names cannot
+ * serve it), the status this API family already uses for an upstream that cannot
+ * complete the operation, and logs at warn. Anything else keeps {@link categorizeError}'s
+ * status and logs at error only when that status is a 5xx.
  */
-function discoveryFailureResponse(requestId: string, error: unknown, defaultMessage: string) {
-  if (error instanceof McpConnectionError) {
+function discoveryFailureResponse(requestId: string, error: unknown) {
+  if (isMcpServerUnavailableError(error)) {
     logger.warn(`[${requestId}] MCP server unavailable for tool discovery`, {
       error: getErrorMessage(error),
     })
-    return createMcpErrorResponse(error, defaultMessage, 422)
+    return createMcpErrorResponse(error, 'Failed to discover MCP tools', 422)
   }
   const { message, status } = categorizeError(error)
   if (status >= 500) {
-    logger.error(`[${requestId}] ${defaultMessage}:`, error)
+    logger.error(`[${requestId}] Error discovering MCP tools:`, error)
   } else {
-    logger.warn(`[${requestId}] ${defaultMessage}`, { error: getErrorMessage(error), status })
+    logger.warn(`[${requestId}] Failed to discover MCP tools`, {
+      error: getErrorMessage(error),
+      status,
+    })
   }
-  return createMcpErrorResponse(new Error(message), defaultMessage, status)
+  return createMcpErrorResponse(new Error(message), 'Failed to discover MCP tools', status)
 }
 
 async function settleWithConcurrency<T, R>(
@@ -134,7 +139,7 @@ export const GET = withRouteHandler(
       ) {
         return createMcpErrorResponse(error, 'OAuth re-authorization required', 401)
       }
-      return discoveryFailureResponse(requestId, error, 'Failed to discover MCP tools')
+      return discoveryFailureResponse(requestId, error)
     }
   })
 )
@@ -199,7 +204,9 @@ export const POST = withRouteHandler(
       ) {
         return createMcpErrorResponse(error, 'OAuth re-authorization required', 401)
       }
-      return discoveryFailureResponse(requestId, error, 'Failed to refresh tool discovery')
+      logger.error(`[${requestId}] Error refreshing tool discovery:`, error)
+      const { message, status } = categorizeError(error)
+      return createMcpErrorResponse(new Error(message), 'Failed to refresh tool discovery', status)
     }
   })
 )
@@ -1,17 +1,12 @@
 import { UnauthorizedError } from '@modelcontextprotocol/sdk/client/auth.js'
-import { StreamableHTTPError } from '@modelcontextprotocol/sdk/client/streamableHttp.js'
-import { McpError as McpSdkError } from '@modelcontextprotocol/sdk/types.js'
 import { type V2McpServer, v2McpServerSchema } from '@/lib/api/contracts/v2/mcp-servers'
 import { createV2ResourceConcealmentPolicy, type V2ErrorPolicy } from '@/lib/api/server/routes'
 import { isTimeoutError } from '@/lib/core/execution-limits'
 import { McpOauthRedirectRequired } from '@/lib/mcp/oauth'
 import { projectMcpHeaders } from '@/lib/mcp/projection'
 import type { McpServerRow } from '@/lib/mcp/queries'
-import {
-  McpConnectionError,
-  McpOauthAuthorizationRequiredError,
-  McpServerCooldownError,
-} from '@/lib/mcp/types'
+import { McpOauthAuthorizationRequiredError, McpServerCooldownError } from '@/lib/mcp/types'
+import { isMcpServerUnavailableError } from '@/lib/mcp/utils'
 import { v2Error } from '@/app/api/v2/lib/response'
 
 /**
@@ -116,12 +111,7 @@ export const v2McpToolDiscoveryErrorPolicy = {
       )
     }
 
-    if (
-      isTimeoutError(error) ||
-      error instanceof McpConnectionError ||
-      error instanceof McpSdkError ||
-      error instanceof StreamableHTTPError
-    ) {
+    if (isMcpServerUnavailableError(error)) {
       return v2Error('SERVICE_UNAVAILABLE', unreachableServerMessage(error))
     }
 
 
@@ -1,4 +1,5 @@
 import { resetUrlsMock, urlsMockFns } from '@sim/testing'
+import { createRouteContext } from '@sim/testing/helpers/http'
 import { authInternalMock, authInternalMockFns } from '@sim/testing/mocks/auth-internal.mock'
 import { hybridAuthMockFns } from '@sim/testing/mocks/hybrid-auth.mock'
 import { utilsHelpersMock, utilsHelpersMockFns } from '@sim/testing/mocks/utils-helpers.mock'
@@ -133,7 +134,8 @@ describe('maskPIIBatchViaHttp', () => {
         async (url: string, init: { body: string; headers: Record<string, string> }) => {
           if (url.startsWith('http://app.internal:3000')) {
             return maskBatchRoute(
-              new NextRequest(url, { method: 'POST', body: init.body, headers: init.headers })
+              new NextRequest(url, { method: 'POST', body: init.body, headers: init.headers }),
+              createRouteContext({})
             )
           }
           const { texts } = JSON.parse(init.body) as { texts: string[] }
 
@@ -1,7 +1,9 @@
 import { UnauthorizedError } from '@modelcontextprotocol/sdk/client/auth.js'
+import { StreamableHTTPError } from '@modelcontextprotocol/sdk/client/streamableHttp.js'
+import { McpError as McpSdkError } from '@modelcontextprotocol/sdk/types.js'
 import { generateShortId } from '@sim/utils/id'
 import { NextResponse } from 'next/server'
-import { DEFAULT_EXECUTION_TIMEOUT_MS } from '@/lib/core/execution-limits'
+import { DEFAULT_EXECUTION_TIMEOUT_MS, isTimeoutError } from '@/lib/core/execution-limits'
 import {
   type McpApiResponse,
   McpConnectionError,
@@ -136,6 +138,23 @@ export function mcpOrchestrationStatus(errorCode: string | undefined): number {
   return 500
 }
 
+/**
+ * Reports whether a registered MCP server failed to answer usefully: it could not be
+ * reached, timed out, is cooling down after a recent failure, or answered `tools/list`
+ * with a protocol or HTTP error. Typed only, never matched on message text, because
+ * `McpConnectionError` interpolates the server's display name into its message. Check
+ * authorization errors first: `UnauthorizedError` is not one of these, but a caller that
+ * wants to answer reauthorization separately must do so before asking.
+ */
+export function isMcpServerUnavailableError(error: unknown): boolean {
+  return (
+    isTimeoutError(error) ||
+    error instanceof McpConnectionError ||
+    error instanceof McpSdkError ||
+    error instanceof StreamableHTTPError
+  )
+}
+
 /**
  * Enhanced error categorization for more specific HTTP status codes.
  * Returns safe, generic messages to prevent leaking internal details.
 
@@ -210,9 +210,6 @@
   "apps/sim/app/api/mcp/oauth/callback/route.test.ts": {
     "TS2554": 7
   },
-  "apps/sim/app/api/mcp/oauth/start/route.test.ts": {
-    "TS2554": 5
-  },
   "apps/sim/app/api/mcp/serve/[serverId]/route.test.ts": {
     "TS2322": 2
   },