Design Patterns MCP Server

Instructions

Implementation Reference

• src/mcp-server.ts:188-209 (registration)

  Registration of the 'search_patterns' tool in the MCP server's tool list, including description and input schema
  name: 'search_patterns', description: 'Search patterns by keyword or semantic similarity', inputSchema: { type: 'object', properties: { query: { type: 'string', description: 'Search query', }, searchType: { type: 'string', enum: ['keyword', 'semantic', 'hybrid'], default: 'hybrid', }, limit: { type: 'number', default: 10, }, }, required: ['query'], }, },
• src/mcp-server.ts:353-383 (handler)

  Handler function for executing the search_patterns tool: validates input, performs semantic search via SemanticSearchService, and formats results as text response
  private async handleSearchPatterns(args: unknown): Promise<CallToolResult> { const validatedArgs = InputValidator.validateSearchPatternsArgs(args); const query = { text: validatedArgs.query, filters: {}, options: { limit: validatedArgs.limit, includeMetadata: true, }, }; const results = await this.semanticSearch.search(query); return { content: [ { type: 'text', text: `Search results for "${validatedArgs.query}":\n\n` + results .map( (result, index) => `${index + 1}. **${result.pattern.name}** (${result.pattern.category})\n` + ` Score: ${(result.score * 100).toFixed(1)}%\n` + ` Description: ${result.pattern.description}\n` ) .join('\n'), }, ], }; }
• src/types/mcp-args.ts:37-51 (schema)

  TypeScript interface definition and type guard for SearchPatternsArgs used in tool input validation
  export interface SearchPatternsArgs { query: string; search_type?: 'keyword' | 'semantic' | 'hybrid'; category_filter?: string[]; limit?: number; } export function isSearchPatternsArgs(args: unknown): args is SearchPatternsArgs { if (typeof args !== 'object' || args === null) return false; const a = args as Record<string, unknown>; return typeof a.query === 'string' && (a.search_type === undefined || ['keyword', 'semantic', 'hybrid'].includes(a.search_type as string)) && (a.category_filter === undefined || Array.isArray(a.category_filter)) && (a.limit === undefined || typeof a.limit === 'number'); }
• src/lib/mcp-tools.ts:932-936 (registration)

  Tool dispatch case in MCPToolsHandler.handleToolCall that routes to handler
  case 'search_patterns': if (!isSearchPatternsArgs(args)) { throw new Error('Invalid arguments for search_patterns tool'); } return await this.handleSearchPatterns(args);
• src/lib/mcp-tools.ts:1070-1122 (handler)

  Comprehensive hybrid search handler supporting keyword, semantic, and hybrid search modes with result merging (alternative implementation in lib)
  private async handleSearchPatterns(args: SearchPatternsArgs): Promise<Record<string, unknown>> { // Validate input if (!args.query || typeof args.query !== 'string' || args.query.length < 2) { throw new Error('Query must be at least 2 characters long'); } const searchType = args.search_type ?? 'hybrid'; const limit = Math.min(args.limit ?? 10, 50); try { let results: SearchResult[]; if (searchType === 'semantic') { // Use semantic search results = await this.config.semanticSearch.search(args.query, { limit, filters: args.category_filter ? { categories: args.category_filter } : undefined, }); } else if (searchType === 'keyword') { // Use keyword search results = await this.config.databaseManager.searchPatterns(args.query, { limit, filters: args.category_filter ? { categories: args.category_filter } : undefined, }); } else { // Hybrid search const semanticResults = await this.config.semanticSearch.search(args.query, { limit: Math.ceil(limit / 2), filters: args.category_filter ? { categories: args.category_filter } : undefined, }); const keywordResults = await this.config.databaseManager.searchPatterns(args.query, { limit: Math.ceil(limit / 2), filters: args.category_filter ? { categories: args.category_filter } : undefined, }); // Merge and deduplicate results results = this.mergeSearchResults(semanticResults, keywordResults, limit); } return { patterns: results, total_results: results.length, search_type: searchType, limit, timestamp: new Date().toISOString(), }; } catch (error) { throw new Error( `Pattern search failed: ${error instanceof Error ? error.message : String(error)}` ); } }