import { ClientRequest, CompatibilityCallToolResult, CompatibilityCallToolResultSchema, CreateMessageResult, EmptyResultSchema, GetPromptResultSchema, ListPromptsResultSchema, ListResourcesResultSchema, ListResourceTemplatesResultSchema, ListToolsResultSchema, ReadResourceResultSchema, Resource, ResourceTemplate, Root, ServerNotification, Tool, LoggingLevel, } from "@modelcontextprotocol/sdk/types.js"; import { OAuthTokensSchema } from "@modelcontextprotocol/sdk/shared/auth.js"; import { SESSION_KEYS, getServerSpecificKey } from "./lib/constants"; import { AuthDebuggerState, EMPTY_DEBUGGER_STATE } from "./lib/auth-types"; import { OAuthStateMachine } from "./lib/oauth-state-machine"; import { cacheToolOutputSchemas } from "./utils/schemaUtils"; import React, { Suspense, useCallback, useEffect, useRef, useState, } from "react"; import { useConnection } from "./lib/hooks/useConnection"; import { useDraggablePane, useDraggableSidebar, } from "./lib/hooks/useDraggablePane"; import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs"; import { Button } from "@/components/ui/button"; import { Bell, Files, FolderTree, Hammer, Hash, Key, MessageSquare, } from "lucide-react"; import { z } from "zod"; import "./App.css"; import AuthDebugger from "./components/AuthDebugger"; import ConsoleTab from "./components/ConsoleTab"; import HistoryAndNotifications from "./components/HistoryAndNotifications"; import PingTab from "./components/PingTab"; import PromptsTab, { Prompt } from "./components/PromptsTab"; import ResourcesTab from "./components/ResourcesTab"; import RootsTab from "./components/RootsTab"; import SamplingTab, { PendingRequest } from "./components/SamplingTab"; import Sidebar from "./components/Sidebar"; import ToolsTab from "./components/ToolsTab"; import { InspectorConfig } from "./lib/configurationTypes"; import { getMCPProxyAddress, getMCPProxyAuthToken, getInitialSseUrl, getInitialTransportType, getInitialCommand, getInitialArgs, initializeInspectorConfig, saveInspectorConfig, } from "./utils/configUtils"; import ElicitationTab, { PendingElicitationRequest, ElicitationResponse, } from "./components/ElicitationTab"; import { CustomHeaders, migrateFromLegacyAuth, } from "./lib/types/customHeaders"; const CONFIG_LOCAL_STORAGE_KEY = "inspectorConfig_v1"; const App = () => { const [resources, setResources] = useState([]); const [resourceTemplates, setResourceTemplates] = useState< ResourceTemplate[] >([]); const [resourceContent, setResourceContent] = useState(""); const [resourceContentMap, setResourceContentMap] = useState< Record >({}); const [prompts, setPrompts] = useState([]); const [promptContent, setPromptContent] = useState(""); const [tools, setTools] = useState([]); const [toolResult, setToolResult] = useState(null); const [errors, setErrors] = useState>({ resources: null, prompts: null, tools: null, }); const [command, setCommand] = useState(getInitialCommand); const [args, setArgs] = useState(getInitialArgs); const [sseUrl, setSseUrl] = useState(getInitialSseUrl); const [transportType, setTransportType] = useState< "stdio" | "sse" | "streamable-http" >(getInitialTransportType); const [logLevel, setLogLevel] = useState("debug"); const [notifications, setNotifications] = useState([]); const [roots, setRoots] = useState([]); const [env, setEnv] = useState>({}); const [config, setConfig] = useState(() => initializeInspectorConfig(CONFIG_LOCAL_STORAGE_KEY), ); const [bearerToken, setBearerToken] = useState(() => { return localStorage.getItem("lastBearerToken") || ""; }); const [headerName, setHeaderName] = useState(() => { return localStorage.getItem("lastHeaderName") || ""; }); const [oauthClientId, setOauthClientId] = useState(() => { return localStorage.getItem("lastOauthClientId") || ""; }); const [oauthScope, setOauthScope] = useState(() => { return localStorage.getItem("lastOauthScope") || ""; }); // Custom headers state with migration from legacy auth const [customHeaders, setCustomHeaders] = useState(() => { const savedHeaders = localStorage.getItem("lastCustomHeaders"); if (savedHeaders) { try { return JSON.parse(savedHeaders); } catch (error) { console.warn( `Failed to parse custom headers: "${savedHeaders}", will try legacy migration`, error, ); // Fall back to migration if JSON parsing fails } } // Migrate from legacy auth if available const legacyToken = localStorage.getItem("lastBearerToken") || ""; const legacyHeaderName = localStorage.getItem("lastHeaderName") || ""; if (legacyToken) { return migrateFromLegacyAuth(legacyToken, legacyHeaderName); } // Default to Authorization: Bearer as the most common case return [ { name: "Authorization", value: "Bearer ", enabled: true, }, ]; }); const [pendingSampleRequests, setPendingSampleRequests] = useState< Array< PendingRequest & { resolve: (result: CreateMessageResult) => void; reject: (error: Error) => void; } > >([]); const [pendingElicitationRequests, setPendingElicitationRequests] = useState< Array< PendingElicitationRequest & { resolve: (response: ElicitationResponse) => void; decline: (error: Error) => void; } > >([]); const [isAuthDebuggerVisible, setIsAuthDebuggerVisible] = useState(false); const [authState, setAuthState] = useState(EMPTY_DEBUGGER_STATE); const updateAuthState = (updates: Partial) => { setAuthState((prev) => ({ ...prev, ...updates })); }; const nextRequestId = useRef(0); const rootsRef = useRef([]); const [selectedResource, setSelectedResource] = useState( null, ); const [resourceSubscriptions, setResourceSubscriptions] = useState< Set >(new Set()); const [selectedPrompt, setSelectedPrompt] = useState(null); const [selectedTool, setSelectedTool] = useState(null); const [nextResourceCursor, setNextResourceCursor] = useState< string | undefined >(); const [nextResourceTemplateCursor, setNextResourceTemplateCursor] = useState< string | undefined >(); const [nextPromptCursor, setNextPromptCursor] = useState< string | undefined >(); const [nextToolCursor, setNextToolCursor] = useState(); const progressTokenRef = useRef(0); const [activeTab, setActiveTab] = useState(() => { const hash = window.location.hash.slice(1); const initialTab = hash || "resources"; return initialTab; }); const currentTabRef = useRef(activeTab); const lastToolCallOriginTabRef = useRef(activeTab); useEffect(() => { currentTabRef.current = activeTab; }, [activeTab]); const { height: historyPaneHeight, handleDragStart } = useDraggablePane(300); const { width: sidebarWidth, isDragging: isSidebarDragging, handleDragStart: handleSidebarDragStart, } = useDraggableSidebar(320); const { connectionStatus, serverCapabilities, mcpClient, requestHistory, clearRequestHistory, makeRequest, sendNotification, handleCompletion, completionsSupported, connect: connectMcpServer, disconnect: disconnectMcpServer, } = useConnection({ transportType, command, args, sseUrl, env, customHeaders, oauthClientId, oauthScope, config, onNotification: (notification) => { setNotifications((prev) => [...prev, notification as ServerNotification]); }, onPendingRequest: (request, resolve, reject) => { setPendingSampleRequests((prev) => [ ...prev, { id: nextRequestId.current++, request, resolve, reject }, ]); }, onElicitationRequest: (request, resolve) => { const currentTab = lastToolCallOriginTabRef.current; setPendingElicitationRequests((prev) => [ ...prev, { id: nextRequestId.current++, request: { id: nextRequestId.current, message: request.params.message, requestedSchema: request.params.requestedSchema, }, originatingTab: currentTab, resolve, decline: (error: Error) => { console.error("Elicitation request rejected:", error); }, }, ]); setActiveTab("elicitations"); window.location.hash = "elicitations"; }, getRoots: () => rootsRef.current, defaultLoggingLevel: logLevel, }); useEffect(() => { if (serverCapabilities) { const hash = window.location.hash.slice(1); const validTabs = [ ...(serverCapabilities?.resources ? ["resources"] : []), ...(serverCapabilities?.prompts ? ["prompts"] : []), ...(serverCapabilities?.tools ? ["tools"] : []), "ping", "sampling", "elicitations", "roots", "auth", ]; const isValidTab = validTabs.includes(hash); if (!isValidTab) { const defaultTab = serverCapabilities?.resources ? "resources" : serverCapabilities?.prompts ? "prompts" : serverCapabilities?.tools ? "tools" : "ping"; setActiveTab(defaultTab); window.location.hash = defaultTab; } } }, [serverCapabilities]); useEffect(() => { localStorage.setItem("lastCommand", command); }, [command]); useEffect(() => { localStorage.setItem("lastArgs", args); }, [args]); useEffect(() => { localStorage.setItem("lastSseUrl", sseUrl); }, [sseUrl]); useEffect(() => { localStorage.setItem("lastTransportType", transportType); }, [transportType]); useEffect(() => { if (bearerToken) { localStorage.setItem("lastBearerToken", bearerToken); } else { localStorage.removeItem("lastBearerToken"); } }, [bearerToken]); useEffect(() => { if (headerName) { localStorage.setItem("lastHeaderName", headerName); } else { localStorage.removeItem("lastHeaderName"); } }, [headerName]); useEffect(() => { localStorage.setItem("lastCustomHeaders", JSON.stringify(customHeaders)); }, [customHeaders]); // Auto-migrate from legacy auth when custom headers are empty but legacy auth exists useEffect(() => { if (customHeaders.length === 0 && (bearerToken || headerName)) { const migratedHeaders = migrateFromLegacyAuth(bearerToken, headerName); if (migratedHeaders.length > 0) { setCustomHeaders(migratedHeaders); // Clear legacy auth after migration setBearerToken(""); setHeaderName(""); } } }, [bearerToken, headerName, customHeaders, setCustomHeaders]); useEffect(() => { localStorage.setItem("lastOauthClientId", oauthClientId); }, [oauthClientId]); useEffect(() => { localStorage.setItem("lastOauthScope", oauthScope); }, [oauthScope]); useEffect(() => { saveInspectorConfig(CONFIG_LOCAL_STORAGE_KEY, config); }, [config]); const onOAuthConnect = useCallback( (serverUrl: string) => { setSseUrl(serverUrl); setIsAuthDebuggerVisible(false); void connectMcpServer(); }, [connectMcpServer], ); const onOAuthDebugConnect = useCallback( async ({ authorizationCode, errorMsg, restoredState, }: { authorizationCode?: string; errorMsg?: string; restoredState?: AuthDebuggerState; }) => { setIsAuthDebuggerVisible(true); if (errorMsg) { updateAuthState({ latestError: new Error(errorMsg), }); return; } if (restoredState && authorizationCode) { let currentState: AuthDebuggerState = { ...restoredState, authorizationCode, oauthStep: "token_request", isInitiatingAuth: true, statusMessage: null, latestError: null, }; try { const stateMachine = new OAuthStateMachine(sseUrl, (updates) => { currentState = { ...currentState, ...updates }; }); while ( currentState.oauthStep !== "complete" && currentState.oauthStep !== "authorization_code" ) { await stateMachine.executeStep(currentState); } if (currentState.oauthStep === "complete") { updateAuthState({ ...currentState, statusMessage: { type: "success", message: "Authentication completed successfully", }, isInitiatingAuth: false, }); } } catch (error) { console.error("OAuth continuation error:", error); updateAuthState({ latestError: error instanceof Error ? error : new Error(String(error)), statusMessage: { type: "error", message: `Failed to complete OAuth flow: ${error instanceof Error ? error.message : String(error)}`, }, isInitiatingAuth: false, }); } } else if (authorizationCode) { updateAuthState({ authorizationCode, oauthStep: "token_request", }); } }, [sseUrl], ); useEffect(() => { const loadOAuthTokens = async () => { try { if (sseUrl) { const key = getServerSpecificKey(SESSION_KEYS.TOKENS, sseUrl); const tokens = sessionStorage.getItem(key); if (tokens) { const parsedTokens = await OAuthTokensSchema.parseAsync( JSON.parse(tokens), ); updateAuthState({ oauthTokens: parsedTokens, oauthStep: "complete", }); } } } catch (error) { console.error("Error loading OAuth tokens:", error); } }; loadOAuthTokens(); }, [sseUrl]); useEffect(() => { const headers: HeadersInit = {}; const { token: proxyAuthToken, header: proxyAuthTokenHeader } = getMCPProxyAuthToken(config); if (proxyAuthToken) { headers[proxyAuthTokenHeader] = `Bearer ${proxyAuthToken}`; } fetch(`${getMCPProxyAddress(config)}/config`, { headers }) .then((response) => response.json()) .then((data) => { setEnv(data.defaultEnvironment); if (data.defaultCommand) { setCommand(data.defaultCommand); } if (data.defaultArgs) { setArgs(data.defaultArgs); } if (data.defaultTransport) { setTransportType( data.defaultTransport as "stdio" | "sse" | "streamable-http", ); } if (data.defaultServerUrl) { setSseUrl(data.defaultServerUrl); } }) .catch((error) => console.error("Error fetching default environment:", error), ); }, [config]); useEffect(() => { rootsRef.current = roots; }, [roots]); useEffect(() => { if (mcpClient && !window.location.hash) { const defaultTab = serverCapabilities?.resources ? "resources" : serverCapabilities?.prompts ? "prompts" : serverCapabilities?.tools ? "tools" : "ping"; window.location.hash = defaultTab; } else if (!mcpClient && window.location.hash) { // Clear hash when disconnected - completely remove the fragment window.history.replaceState( null, "", window.location.pathname + window.location.search, ); } }, [mcpClient, serverCapabilities]); useEffect(() => { const handleHashChange = () => { const hash = window.location.hash.slice(1); if (hash && hash !== activeTab) { setActiveTab(hash); } }; window.addEventListener("hashchange", handleHashChange); return () => window.removeEventListener("hashchange", handleHashChange); }, [activeTab]); const handleApproveSampling = (id: number, result: CreateMessageResult) => { setPendingSampleRequests((prev) => { const request = prev.find((r) => r.id === id); request?.resolve(result); return prev.filter((r) => r.id !== id); }); }; const handleRejectSampling = (id: number) => { setPendingSampleRequests((prev) => { const request = prev.find((r) => r.id === id); request?.reject(new Error("Sampling request rejected")); return prev.filter((r) => r.id !== id); }); }; const handleResolveElicitation = ( id: number, response: ElicitationResponse, ) => { setPendingElicitationRequests((prev) => { const request = prev.find((r) => r.id === id); if (request) { request.resolve(response); if (request.originatingTab) { const originatingTab = request.originatingTab; const validTabs = [ ...(serverCapabilities?.resources ? ["resources"] : []), ...(serverCapabilities?.prompts ? ["prompts"] : []), ...(serverCapabilities?.tools ? ["tools"] : []), "ping", "sampling", "elicitations", "roots", "auth", ]; if (validTabs.includes(originatingTab)) { setActiveTab(originatingTab); window.location.hash = originatingTab; setTimeout(() => { setActiveTab(originatingTab); window.location.hash = originatingTab; }, 100); } } } return prev.filter((r) => r.id !== id); }); }; const clearError = (tabKey: keyof typeof errors) => { setErrors((prev) => ({ ...prev, [tabKey]: null })); }; const sendMCPRequest = async ( request: ClientRequest, schema: T, tabKey?: keyof typeof errors, ) => { try { const response = await makeRequest(request, schema); if (tabKey !== undefined) { clearError(tabKey); } return response; } catch (e) { const errorString = (e as Error).message ?? String(e); if (tabKey !== undefined) { setErrors((prev) => ({ ...prev, [tabKey]: errorString, })); } throw e; } }; const listResources = async () => { const response = await sendMCPRequest( { method: "resources/list" as const, params: nextResourceCursor ? { cursor: nextResourceCursor } : {}, }, ListResourcesResultSchema, "resources", ); setResources(resources.concat(response.resources ?? [])); setNextResourceCursor(response.nextCursor); }; const listResourceTemplates = async () => { const response = await sendMCPRequest( { method: "resources/templates/list" as const, params: nextResourceTemplateCursor ? { cursor: nextResourceTemplateCursor } : {}, }, ListResourceTemplatesResultSchema, "resources", ); setResourceTemplates( resourceTemplates.concat(response.resourceTemplates ?? []), ); setNextResourceTemplateCursor(response.nextCursor); }; const getPrompt = async (name: string, args: Record = {}) => { lastToolCallOriginTabRef.current = currentTabRef.current; const response = await sendMCPRequest( { method: "prompts/get" as const, params: { name, arguments: args }, }, GetPromptResultSchema, "prompts", ); setPromptContent(JSON.stringify(response, null, 2)); }; const readResource = async (uri: string) => { lastToolCallOriginTabRef.current = currentTabRef.current; const response = await sendMCPRequest( { method: "resources/read" as const, params: { uri }, }, ReadResourceResultSchema, "resources", ); const content = JSON.stringify(response, null, 2); setResourceContent(content); setResourceContentMap((prev) => ({ ...prev, [uri]: content, })); }; const subscribeToResource = async (uri: string) => { if (!resourceSubscriptions.has(uri)) { await sendMCPRequest( { method: "resources/subscribe" as const, params: { uri }, }, z.object({}), "resources", ); const clone = new Set(resourceSubscriptions); clone.add(uri); setResourceSubscriptions(clone); } }; const unsubscribeFromResource = async (uri: string) => { if (resourceSubscriptions.has(uri)) { await sendMCPRequest( { method: "resources/unsubscribe" as const, params: { uri }, }, z.object({}), "resources", ); const clone = new Set(resourceSubscriptions); clone.delete(uri); setResourceSubscriptions(clone); } }; const listPrompts = async () => { const response = await sendMCPRequest( { method: "prompts/list" as const, params: nextPromptCursor ? { cursor: nextPromptCursor } : {}, }, ListPromptsResultSchema, "prompts", ); setPrompts(response.prompts); setNextPromptCursor(response.nextCursor); }; const listTools = async () => { const response = await sendMCPRequest( { method: "tools/list" as const, params: nextToolCursor ? { cursor: nextToolCursor } : {}, }, ListToolsResultSchema, "tools", ); setTools(response.tools); setNextToolCursor(response.nextCursor); cacheToolOutputSchemas(response.tools); }; const callTool = async (name: string, params: Record) => { lastToolCallOriginTabRef.current = currentTabRef.current; try { const response = await sendMCPRequest( { method: "tools/call" as const, params: { name, arguments: params, _meta: { progressToken: progressTokenRef.current++, }, }, }, CompatibilityCallToolResultSchema, "tools", ); setToolResult(response); } catch (e) { const toolResult: CompatibilityCallToolResult = { content: [ { type: "text", text: (e as Error).message ?? String(e), }, ], isError: true, }; setToolResult(toolResult); } }; const handleRootsChange = async () => { await sendNotification({ method: "notifications/roots/list_changed" }); }; const handleClearNotifications = () => { setNotifications([]); }; const sendLogLevelRequest = async (level: LoggingLevel) => { await sendMCPRequest( { method: "logging/setLevel" as const, params: { level }, }, z.object({}), ); setLogLevel(level); }; const AuthDebuggerWrapper = () => ( setIsAuthDebuggerVisible(false)} authState={authState} updateAuthState={updateAuthState} /> ); if (window.location.pathname === "/oauth/callback") { const OAuthCallback = React.lazy( () => import("./components/OAuthCallback"), ); return ( Loading...}> ); } if (window.location.pathname === "/oauth/callback/debug") { const OAuthDebugCallback = React.lazy( () => import("./components/OAuthDebugCallback"), ); return ( Loading...}> ); } return (
{mcpClient ? ( { setActiveTab(value); window.location.hash = value; }} > Resources Prompts Tools Ping Sampling {pendingSampleRequests.length > 0 && ( {pendingSampleRequests.length} )} Elicitations {pendingElicitationRequests.length > 0 && ( {pendingElicitationRequests.length} )} Roots Auth
{!serverCapabilities?.resources && !serverCapabilities?.prompts && !serverCapabilities?.tools ? ( <>

The connected server does not support any MCP capabilities

{ void sendMCPRequest( { method: "ping" as const, }, EmptyResultSchema, ); }} /> ) : ( <> { clearError("resources"); listResources(); }} clearResources={() => { setResources([]); setNextResourceCursor(undefined); }} listResourceTemplates={() => { clearError("resources"); listResourceTemplates(); }} clearResourceTemplates={() => { setResourceTemplates([]); setNextResourceTemplateCursor(undefined); }} readResource={(uri) => { clearError("resources"); readResource(uri); }} selectedResource={selectedResource} setSelectedResource={(resource) => { clearError("resources"); setSelectedResource(resource); }} resourceSubscriptionsSupported={ serverCapabilities?.resources?.subscribe || false } resourceSubscriptions={resourceSubscriptions} subscribeToResource={(uri) => { clearError("resources"); subscribeToResource(uri); }} unsubscribeFromResource={(uri) => { clearError("resources"); unsubscribeFromResource(uri); }} handleCompletion={handleCompletion} completionsSupported={completionsSupported} resourceContent={resourceContent} nextCursor={nextResourceCursor} nextTemplateCursor={nextResourceTemplateCursor} error={errors.resources} /> { clearError("prompts"); listPrompts(); }} clearPrompts={() => { setPrompts([]); setNextPromptCursor(undefined); }} getPrompt={(name, args) => { clearError("prompts"); getPrompt(name, args); }} selectedPrompt={selectedPrompt} setSelectedPrompt={(prompt) => { clearError("prompts"); setSelectedPrompt(prompt); setPromptContent(""); }} handleCompletion={handleCompletion} completionsSupported={completionsSupported} promptContent={promptContent} nextCursor={nextPromptCursor} error={errors.prompts} /> { clearError("tools"); listTools(); }} clearTools={() => { setTools([]); setNextToolCursor(undefined); cacheToolOutputSchemas([]); }} callTool={async (name, params) => { clearError("tools"); setToolResult(null); await callTool(name, params); }} selectedTool={selectedTool} setSelectedTool={(tool) => { clearError("tools"); setSelectedTool(tool); setToolResult(null); }} toolResult={toolResult} nextCursor={nextToolCursor} error={errors.tools} resourceContent={resourceContentMap} onReadResource={(uri: string) => { clearError("resources"); readResource(uri); }} /> { void sendMCPRequest( { method: "ping" as const, }, EmptyResultSchema, ); }} /> )}
) : isAuthDebuggerVisible ? ( (window.location.hash = value)} > ) : (

Connect to an MCP server to start inspecting

Need to configure authentication?

)}
); }; export default App;