Faker MCP Server

````markdown # Implementation Plan: Fake Data Generation MCP Server **Branch**: `001-faker-mcp-server` | **Date**: 2025-11-05 | **Spec**: [spec.md](./spec.md) **Input**: Feature specification from `/specs/001-faker-mcp-server/spec.md` **Note**: This template is filled in by the `/speckit.plan` command. See `.specify/templates/commands/plan.md` for the execution workflow. ## Summary Build an MCP (Model Context Protocol) server in TypeScript using Vite that provides fake/mock data generation capabilities via the Faker library. The server will support basic data generation (names, emails, addresses), structured dataset generation with referential integrity, and custom data patterns for specialized use cases. The implementation emphasizes minimal dependencies, high performance (1000+ records/second), and strict MCP protocol compliance. ## Technical Context **Language/Version**: TypeScript 5.x with strict mode enabled **Primary Dependencies**: @modelcontextprotocol/sdk (MCP SDK), @faker-js/faker (data generation), Vite (build tool) **Storage**: N/A (stateless server, in-memory generation only) **Testing**: Vitest (unit tests), MCP Inspector (protocol compliance testing) **Target Platform**: Node.js 18+ (cross-platform: macOS, Linux, Windows) **Project Type**: Single project (MCP server application) **Performance Goals**: >1000 records/second generation, <200ms p95 API response time, handle 10 concurrent connections **Constraints**: <100MB memory for standard operations (up to 10k records), minimal external dependencies, strict MCP protocol compliance **Scale/Scope**: Single-server deployment, support for datasets up to 10,000 records, 5-10 core data generation tools ## Constitution Check *GATE: Must pass before Phase 0 research. Re-check after Phase 1 design.* **Code Quality Standards**: - [x] All code will follow linting/formatting standards (ESLint + Prettier for TypeScript) - [x] Type hints will be used where applicable (TypeScript strict mode enforced) - [x] Documentation strings planned for all public APIs (JSDoc comments for all exported functions/classes) - [x] Code complexity is justified or will be kept minimal (single project structure, minimal dependencies) **Test-Driven Development**: - [x] Tests will be written before implementation (Vitest for unit tests, MCP Inspector for protocol compliance) - [x] Target 90% code coverage (100% for critical paths - MCP protocol handlers, data generation logic) - [x] Red-Green-Refactor cycle will be followed (test-first approach for all features) - [x] Tests will be independent and fast-running (unit tests <1s, integration tests <10s) **User Experience Consistency**: - [x] CLI interfaces follow standard patterns (MCP server follows standard stdio/SSE transport patterns) - [x] Error messages will be actionable with remediation steps (MCP standard error codes with detailed messages) - [x] Output formats will be consistent (JSON responses following MCP protocol specification) - [x] MCP protocol compliance ensured (strict adherence to MCP spec, validated with MCP Inspector) **Performance Requirements**: - [x] API responses <200ms p95 requirement identified (generation of up to 1000 records in <2s) - [x] Memory usage <100MB for standard operations (datasets up to 10k records) - [x] Performance tests planned for critical paths (benchmark tests for data generation throughput) - [x] Progress indicators planned for long operations (N/A - MCP protocol doesn't support streaming progress, but large operations will be discouraged in docs) ## Project Structure ### Documentation (this feature) ```text specs/[###-feature]/ ├── plan.md # This file (/speckit.plan command output) ├── research.md # Phase 0 output (/speckit.plan command) ├── data-model.md # Phase 1 output (/speckit.plan command) ├── quickstart.md # Phase 1 output (/speckit.plan command) ├── contracts/ # Phase 1 output (/speckit.plan command) └── tasks.md # Phase 2 output (/speckit.tasks command - NOT created by /speckit.plan) ``` ### Source Code (repository root) ```text src/ ├── index.ts # MCP server entry point, transport setup ├── server.ts # MCP server class, tool registration ├── tools/ # MCP tool implementations │ ├── generate-person.ts # Generate person data (name, email, phone, address) │ ├── generate-company.ts # Generate company data │ ├── generate-dataset.ts # Generate structured datasets with schema │ └── generate-custom.ts # Generate custom pattern data ├── generators/ # Core data generation logic │ ├── base-generator.ts # Abstract base generator with faker instance │ ├── person-generator.ts # Person data generation │ ├── company-generator.ts # Company data generation │ ├── dataset-generator.ts # Multi-entity dataset generation │ └── custom-generator.ts # Custom pattern generation ├── types/ # TypeScript type definitions │ ├── schema.ts # Schema definitions for datasets │ ├── requests.ts # Request parameter types │ └── responses.ts # Response data types └── utils/ # Utility functions ├── validators.ts # Input validation helpers └── seed-manager.ts # Seed generation and management tests/ ├── unit/ # Unit tests for generators and utilities │ ├── generators/ │ └── utils/ ├── integration/ # Integration tests for MCP tools │ └── tools/ └── contract/ # MCP protocol compliance tests └── mcp-protocol.test.ts vite.config.ts # Vite configuration tsconfig.json # TypeScript configuration package.json # Dependencies and scripts .eslintrc.json # ESLint configuration .prettierrc # Prettier configuration ``` **Structure Decision**: Single project structure selected as this is a standalone MCP server application with no frontend or mobile components. The structure separates MCP protocol concerns (`tools/`) from core business logic (`generators/`), making the codebase maintainable and testable. The `src/` directory contains all implementation code, while `tests/` mirrors the source structure for clear test organization. ## Complexity Tracking > **Fill ONLY if Constitution Check has violations that must be justified** No violations identified. All constitutional requirements are met within standard complexity bounds.