NCP - Natural Context Provider

#!/usr/bin/env node /** * Base Mock MCP Server * Provides a template for creating realistic MCP servers for testing * These servers respond to MCP protocol but don't actually execute tools */ console.error('[DEBUG] Loading base mock server module...'); // Import SDK modules and debug each import step let Server; let StdioServerTransport; let McpTypes; import { z } from 'zod'; try { const serverModule = await import('@modelcontextprotocol/sdk/server/index.js'); Server = serverModule.Server; console.error('[DEBUG] Successfully loaded Server module'); } catch (err) { console.error('[ERROR] Failed to load Server module:', err); throw err; } try { const stdioModule = await import('@modelcontextprotocol/sdk/server/stdio.js'); StdioServerTransport = stdioModule.StdioServerTransport; console.error('[DEBUG] Successfully loaded StdioServerTransport module'); } catch (err) { console.error('[ERROR] Failed to load StdioServerTransport module:', err); throw err; } try { McpTypes = await import('@modelcontextprotocol/sdk/types.js'); console.error('[DEBUG] Successfully loaded McpTypes module. Exports:', Object.keys(McpTypes)); } catch (err) { console.error('[ERROR] Failed to load McpTypes module:', err); throw err; } // Log exports for debugging console.error('[DEBUG] Available MCP types:', Object.keys(McpTypes)); class MockMCPServer { constructor(serverInfo, tools, resources = [], capabilities = { tools: { listTools: true, callTool: true, find: true, }, resources: {}, }) { console.error('[DEBUG] MockMCPServer constructor called'); console.error('[DEBUG] Server info:', JSON.stringify(serverInfo, null, 2)); console.error('[DEBUG] Capabilities:', JSON.stringify(capabilities, null, 2)); this.serverInfo = serverInfo; // Store server info for reference try { this.server = new Server(serverInfo, { capabilities }); console.error('[DEBUG] Server instance created successfully'); } catch (err) { console.error('[ERROR] Failed to create Server instance:', err); console.error('[ERROR] Error stack:', err.stack); throw err; } this.tools = tools; this.resources = resources; try { this.setupHandlers(); console.error('[DEBUG] Handlers set up successfully'); } catch (err) { console.error('[ERROR] Failed to set up handlers:', err); console.error('[ERROR] Error stack:', err.stack); throw err; } } setupHandlers() { try { console.error('[DEBUG] Setting up server request handlers'); console.error('[DEBUG] McpTypes.ListToolsRequestSchema:', McpTypes.ListToolsRequestSchema); // List available tools this.server.setRequestHandler(McpTypes.ListToolsRequestSchema, async () => ({ tools: this.tools, })); console.error('[DEBUG] Set up tools/list handler'); // Handle tool calls (always return success with mock data) this.server.setRequestHandler(McpTypes.CallToolRequestSchema, async (request) => { const { name, arguments: args } = request.params; // Find the tool const tool = this.tools.find(t => t.name === name); if (!tool) { throw new McpTypes.McpError(McpTypes.ErrorCode.MethodNotFound, `Tool "${name}" not found`); } // Return mock successful response return { content: [ { type: "text", text: `Mock execution of ${name} with args: ${JSON.stringify(args, null, 2)}\n\nThis is a test MCP server - no actual operation was performed.` } ] }; }); console.error('[DEBUG] Set up tools/call handler'); // Handle find requests using standard MCP schema const FindToolsSchema = z.object({ method: z.literal("tools/find"), params: z.object({ query: z.string(), }) }); this.server.setRequestHandler(FindToolsSchema, async (request) => { try { // For the git-server, just return all tools that match the query string const { query } = request.params; const matchingTools = this.tools.filter(tool => tool.name.toLowerCase().includes(query.toLowerCase()) || (tool.description && tool.description.toLowerCase().includes(query.toLowerCase())) ); return { tools: matchingTools }; } catch (err) { console.error('[ERROR] Error in tools/find handler:', err); throw err; } }); console.error('[DEBUG] Set up tools/find handler'); // List resources (if any) this.server.setRequestHandler(McpTypes.ListResourcesRequestSchema, async () => ({ resources: this.resources, })); console.error('[DEBUG] Set up resources/list handler'); // Read resources (if any) this.server.setRequestHandler(McpTypes.ReadResourceRequestSchema, async (request) => { const resource = this.resources.find(r => r.uri === request.params.uri); if (!resource) { throw new McpTypes.McpError(McpTypes.ErrorCode.InvalidRequest, `Resource not found: ${request.params.uri}`); } return { contents: [ { uri: request.params.uri, mimeType: "text/plain", text: `Mock resource content for ${request.params.uri}` } ] }; }); console.error('[DEBUG] Set up resources/read handler'); } catch (err) { console.error('[ERROR] Error in setupHandlers:', err); console.error('[ERROR] Error stack:', err.stack); console.error('[ERROR] Server state:', { serverInfo: this.serverInfo, serverCapabilities: this.server?.capabilities, availableSchemas: Object.keys(McpTypes) }); throw err; } } async run() { try { const name = this.serverInfo.name; console.error('[DEBUG] Starting mock MCP server...'); console.error('[DEBUG] Server name:', name); console.error('[DEBUG] Server info:', JSON.stringify(this.serverInfo, null, 2)); console.error('[DEBUG] Server capabilities:', JSON.stringify(this.server.capabilities, null, 2)); // Validate server is ready for transport if (!this.server) { throw new Error('Server instance not initialized'); } // Set up transport console.error('[DEBUG] Creating StdioServerTransport...'); let transport; try { transport = new StdioServerTransport(); console.error('[DEBUG] StdioServerTransport instance:', transport); console.error('[DEBUG] StdioServerTransport created successfully'); } catch (err) { console.error('[ERROR] Failed to create StdioServerTransport:'); console.error('[ERROR] Error message:', err.message); console.error('[ERROR] Error stack:', err.stack); console.error('[ERROR] Error details:', err); throw err; } // Connect server console.error('[DEBUG] Connecting server to transport...'); try { const connectResult = await this.server.connect(transport); console.error('[DEBUG] Server connected to transport successfully'); console.error('[DEBUG] Connect result:', connectResult); } catch (err) { console.error('[ERROR] Failed to connect server to transport:'); console.error('[ERROR] Error message:', err.message); console.error('[ERROR] Error stack:', err.stack); console.error('[ERROR] Error details:', err); console.error('[ERROR] Server state:', { serverInfo: this.serverInfo, capabilities: this.server.capabilities, transportState: transport }); throw err; } // Signal that we're ready with name and capabilities on both stdout and stderr for robustness const readyMessage = `[READY] ${name}\n`; const readyJson = JSON.stringify({ event: 'ready', name, capabilities: this.server.capabilities, timestamp: Date.now() }); // Signal that we're ready on stdout first (more reliable) console.error('[DEBUG] About to send ready signal to stdout...'); // Buffer outputs to avoid interleaving const outputBuffer = []; outputBuffer.push(readyMessage); outputBuffer.push(readyJson + '\n'); outputBuffer.push(readyMessage); // Write all buffered outputs at once try { process.stdout.write(outputBuffer.join('')); console.error('[DEBUG] Successfully wrote ready signal to stdout'); } catch (err) { console.error('[ERROR] Failed to write to stdout:', err); throw err; } // Then send to stderr for debugging try { process.stderr.write(`[STARTUP] ${name}: sending ready signal\n`); process.stderr.write(readyMessage); process.stderr.write(`[STARTUP] ${name}: ${readyJson}\n`); console.error('[DEBUG] Successfully wrote debug info to stderr'); } catch (err) { console.error('[ERROR] Failed to write to stderr:', err); throw err; } // Add debug info after ready signal process.stderr.write(`[STARTUP] ${name}: adding capabilities info\n`); console.error(`Mock MCP server ${name} running on stdio`); console.error(`[CAPABILITIES] ${JSON.stringify(this.server.capabilities)}`); // Keep the process alive but ensure we can exit const stdin = process.stdin.resume(); stdin.unref(); // Allow process to exit if stdin is the only thing keeping it alive // Set up a startup timeout const startupTimeout = setTimeout(() => { console.error(`[TIMEOUT] ${name} server startup timeout after ${process.uptime()}s`); console.error('[DEBUG] Process state:', { pid: process.pid, uptime: process.uptime(), memory: process.memoryUsage(), connections: this.server?.transport?.connections || [] }); process.exit(1); }, 10000); // Make sure the timeout doesn't keep the process alive startupTimeout.unref(); // Monitor event loop blockage let lastCheck = Date.now(); const blockageCheck = setInterval(() => { const now = Date.now(); const delay = now - lastCheck - 1000; // Should be ~1000ms if (delay > 100) { // Over 100ms delay indicates blockage console.error(`[WARN] Event loop blocked for ${delay}ms in ${name} server`); } lastCheck = now; }, 1000); blockageCheck.unref(); // Don't prevent exit // Handle cleanup process.on('SIGTERM', () => { clearTimeout(startupTimeout); console.error(`[SHUTDOWN] ${this.serverInfo.name}`); process.exit(0); }); // Handle other signals process.on('SIGINT', () => { clearTimeout(startupTimeout); const name = this.server.info?.name || this.serverInfo.name; console.error(`[SHUTDOWN] ${name} (interrupted)`); process.exit(0); }); } catch (error) { const name = this.serverInfo?.name || "unknown"; console.error(`Error starting mock server ${name}:`, error); console.error('Server info:', JSON.stringify(this.serverInfo, null, 2)); console.error('Server capabilities:', JSON.stringify(this.server.capabilities, null, 2)); process.exit(1); } } } export { MockMCPServer };