Pokemon MCP Server

# Pokemon MCP Server - Code Improvements Analysis ## Current Implementation Overview The Pokemon MCP server currently uses a monolithic architecture with the main server logic in `server.ts` (850+ lines) and a single extracted tool class `GetPokemonTool`. The server handles 6 different Pokemon-related tools through direct database queries using better-sqlite3. ### Current getPokemon Tool Flow 1. Validates identifier (numeric ID vs name) 2. Queries main pokemon table 3. Executes 3 additional queries for stats, types, abilities 4. Formats response as markdown text ## Key Areas for Improvement ### 1. Database Query Optimization ⚡ **Current Issue:** - Executes **4 separate queries** per Pokemon request - Each query is a separate database round trip - Inefficient for frequently accessed data **Improvement:** ```sql -- Single optimized query to replace 4 separate queries SELECT p.*, s.stat_name, s.base_stat, s.effort, t.name as type_name, pt.slot as type_slot, a.name as ability_name, pa.is_hidden, pa.slot as ability_slot FROM pokemon p LEFT JOIN stats s ON p.id = s.pokemon_id LEFT JOIN pokemon_types pt ON p.id = pt.pokemon_id LEFT JOIN types t ON pt.type_id = t.id LEFT JOIN pokemon_abilities pa ON p.id = pa.pokemon_id LEFT JOIN abilities a ON pa.ability_id = a.id WHERE p.id = ? OR LOWER(p.name) = LOWER(?) ORDER BY s.stat_name, pt.slot, pa.slot ``` **Expected Impact:** 75% reduction in database queries ### 2. Code Organization & Architecture 🏗️ **Current Issues:** - Monolithic server file (850+ lines) - Duplicate helper methods (`getPokemonData`, `getPokemonStatsData`) - Inconsistent error handling patterns - Mixed concerns (server setup + business logic) **Proposed Structure:** ``` src/ ├── server.ts # Main server setup only ├── database/ │ ├── connection.ts # Database connection management │ ├── queries.ts # Centralized query definitions │ └── models.ts # Data access layer ├── tools/ │ ├── base/ │ │ ├── BaseTool.ts # Abstract base class │ │ └── ToolRegistry.ts # Tool registration system │ ├── getPokemon.ts │ ├── searchPokemon.ts │ └── [other tools] ├── formatters/ │ ├── MarkdownFormatter.ts # Response formatting │ └── JsonFormatter.ts # Alternative formats └── utils/ ├── validators.ts # Input validation └── errors.ts # Error handling utilities ``` ### 3. Performance & Caching 🚀 **Current Issues:** - No query result caching - Prepared statements created on every call - No performance monitoring **Improvements:** - **Query Preparation Cache:** Pre-prepare frequently used queries - **Result Caching:** Cache Pokemon data with TTL (since it's mostly static) - **Connection Optimization:** Reuse prepared statements - **Performance Metrics:** Add query timing and hit rate tracking ```typescript class QueryCache { private preparedQueries = new Map<string, Database.Statement>(); private resultCache = new Map<string, { data: any; timestamp: number }>(); getPreparedQuery(sql: string): Database.Statement { if (!this.preparedQueries.has(sql)) { this.preparedQueries.set(sql, this.db.prepare(sql)); } return this.preparedQueries.get(sql)!; } } ``` ### 4. Response Formatting & Flexibility 📝 **Current Issues:** - Hardcoded markdown formatting in business logic - No support for different output formats - Formatting mixed with data retrieval **Improvements:** - **Formatter Pattern:** Separate data retrieval from presentation - **Multiple Formats:** Support JSON, plain text, structured data - **Template System:** Configurable response templates ```typescript abstract class ResponseFormatter { abstract formatPokemon(pokemon: PokemonData): ToolResponse; } class MarkdownFormatter extends ResponseFormatter { formatPokemon(pokemon: PokemonData): ToolResponse { // Markdown-specific formatting } } ``` ### 5. Type Safety & Data Validation 🛡️ **Current Issues:** - Database results cast to interfaces without validation - Missing null checks on joined data - No runtime type checking **Improvements:** - **Runtime Validation:** Use Zod or similar for type validation - **Null Safety:** Proper handling of missing data - **Error Recovery:** Graceful degradation when data is incomplete ```typescript import { z } from 'zod'; const PokemonSchema = z.object({ id: z.number(), name: z.string(), height: z.number(), weight: z.number(), // ... other fields }); const validatePokemon = (data: unknown): Pokemon => { return PokemonSchema.parse(data); }; ``` ### 6. Error Handling & Logging 📊 **Current Issues:** - Basic error handling with console.error - No structured logging - Limited error context **Improvements:** - **Structured Logging:** Use proper logging library (winston, pino) - **Error Context:** Include request IDs, timing, query details - **Health Monitoring:** Database connection health checks - **Graceful Degradation:** Fallback responses for partial failures ## Implementation Priority ### Phase 1: High Impact, Low Risk 1. **Extract Tool Classes** - Move all tools to separate files 2. **Database Query Optimization** - Consolidate getPokemon queries 3. **Prepared Statement Caching** - Improve query performance ### Phase 2: Architecture Improvements 1. **Response Formatter Pattern** - Separate formatting from logic 2. **Centralized Query Management** - Move queries to dedicated module 3. **Input Validation** - Add runtime type checking ### Phase 3: Advanced Features 1. **Result Caching** - Add intelligent caching layer 2. **Multiple Output Formats** - Support JSON, structured responses 3. **Performance Monitoring** - Add metrics and health checks ## Expected Benefits - **Performance:** 75% reduction in database queries for getPokemon - **Maintainability:** Modular architecture, easier to test and extend - **Reliability:** Better error handling and data validation - **Developer Experience:** Type safety, consistent patterns - **Scalability:** Caching and optimization for higher loads ## Files to Modify 1. `packages/pokemon-mcp-server/server.ts` - Refactor and extract tools 2. `packages/pokemon-mcp-server/src/tools/getPokemon.ts` - Optimize queries 3. Create new files for database, formatting, and validation modules 4. Update tests to match new architecture This refactoring will transform the server from a monolithic implementation into a well-structured, performant, and maintainable MCP server.