MCP Server Boilerplate

import { GetPromptRequest, GetPromptRequestSchema, GetPromptResult, ListPromptsRequestSchema, } from '@modelcontextprotocol/sdk/types.js'; import { loggingContext } from '@/core/server'; import { promptLoader } from '@/prompts/loader'; import { PromptContext } from '@/prompts/types'; export function setupPromptsHandlers(promptContext: PromptContext): void { const server = promptContext.server; if (!server) { throw new Error('Server not found'); } // List available prompts server.setRequestHandler(ListPromptsRequestSchema, () => { const prompts = promptLoader.getPromptDefinitions(); return Promise.resolve({ prompts: prompts.map(prompt => ({ name: prompt.name, description: prompt.description, arguments: prompt.arguments, })), }); }); // Get prompt server.setRequestHandler( GetPromptRequestSchema, async (request: GetPromptRequest) => { return handlePromptCall(request, promptContext); } ); } export function loadPrompts(): void { try { promptLoader.loadAllPrompts(); loggingContext.log('info', 'All prompts loaded successfully'); } catch (error) { loggingContext.log('error', 'Failed to load prompts', { error: { message: error instanceof Error ? error.message : 'Unknown error', stack: error instanceof Error ? error.stack : undefined, }, }); throw error; } } async function handlePromptCall( request: GetPromptRequest, promptContext: PromptContext ): Promise<GetPromptResult> { const server = promptContext.server; if (!server) { throw new Error('Server not found'); } const { name } = request.params; const prompt = promptLoader.getPrompt(name); if (!prompt) { throw new Error(`Prompt not found: ${name}`); } try { // Add progress token to context if provided const requestWithMeta = request as GetPromptRequest & { _meta?: { progressToken?: string | number }; }; // If no progress token is provided, generate a random one const progressToken = requestWithMeta._meta?.progressToken ?? Math.random().toString(36).substring(2, 15); loggingContext.setContextValue('progressToken', progressToken); const promptContextWithProgressToken: PromptContext = { ...promptContext, progressToken, }; const generator = prompt.process(request, promptContextWithProgressToken); let finalResult: GetPromptResult | null = null; // Get the result from the generator and assign it to the final result for await (const result of generator) { finalResult = result; } // Ensure we have at least one result finalResult ??= { messages: [], }; return finalResult; } catch (error: unknown) { loggingContext.log('error', 'Prompt call failed', { data: { promptName: name, error: error instanceof Error ? error.message : 'Unknown error', stack: error instanceof Error ? error.stack : undefined, }, }); return { messages: [ { role: 'user', content: { type: 'text', text: `Prompt call failed: ${ error instanceof Error ? error.message : 'Unknown error' }`, }, }, ], }; } }