# MCP Server Builder Patterns > Create MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. The quality of an MCP server is measured by how well it enables LLMs to acc Parent: [MCP Server Development](https://llms-explorer.com/tree/mcp-server-development/) · 15 facets · 123 facts · page: https://llms-explorer.com/tree/mcp-server-builder-patterns/ ## Overview - Create MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. The quality of an MCP server is measured by how well it enables LLMs to accomplish real-world tasks. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#overview) ## 🚀 High-Level Workflow - Creating a high-quality MCP server involves four main phases: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#-high-level-workflow) ## Phase 1: Deep Research and Planning - #### 1.1 Understand Modern MCP Design — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - API Coverage vs. Workflow Tools: Balance comprehensive API endpoint coverage with specialized workflow tools. Workflow tools can be more convenient for specific tasks, while comprehensive coverage gives agents flexibility to compose operations. Performance varies by client—some clients benefit from code execution that combines basic tools, while others work better with higher-level workflows. When uncertain, prioritize comprehensive API coverage. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Tool Naming and Discoverability: Clear, descriptive tool names help agents find the right tools quickly. Use consistent prefixes (e.g., github_create_issue, github_list_repos) and action-oriented naming. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Context Management: Agents benefit from concise tool descriptions and the ability to filter/paginate results. Design tools that return focused, relevant data. Some clients support code execution which can help agents filter and process data efficiently. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Actionable Error Messages: Error messages should guide agents toward solutions with specific suggestions and next steps. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - #### 1.2 Study MCP Protocol Documentation — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Navigate the MCP specification: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Start with the sitemap to find relevant pages: https://modelcontextprotocol.io/sitemap.xml — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Then fetch specific pages with .md suffix for markdown format (e.g., https://modelcontextprotocol.io/specification/draft.md). — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Specification overview and architecture — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Transport mechanisms (streamable HTTP, stdio) — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Tool, resource, and prompt definitions — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - #### 1.3 Study Framework Documentation — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Recommended stack: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Language: TypeScript (high-quality SDK support and good compatibility in many execution environments e.g. MCPB. Plus AI models are good at generating TypeScript code, benefiting from its broad usage, static typing and good linting tools) — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Transport: Streamable HTTP for remote servers, using stateless JSON (simpler to scale and maintain, as opposed to stateful sessions and streaming responses). stdio for local servers. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Load framework documentation: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - MCP Best Practices: 📋 View Best Practices - Core guidelines — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - For TypeScript (recommended): — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - TypeScript SDK: Use WebFetch to load https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/main/README.md — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - ⚡ TypeScript Guide - TypeScript patterns and examples — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Python SDK: Use WebFetch to load https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.md — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - 🐍 Python Guide - Python patterns and examples — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - #### 1.4 Plan Your Implementation — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Understand the API: Review the service's API documentation to identify key endpoints, authentication requirements, and data models. Use web search and WebFetch as needed. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) - Tool Selection: Prioritize comprehensive API coverage. List endpoints to implement, starting with the most common operations. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-1-deep-research-and-planning) ## Phase 2: Implementation - #### 2.1 Set Up Project Structure — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - See language-specific guides for project setup: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - ⚡ TypeScript Guide - Project structure, package.json, tsconfig.json — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - 🐍 Python Guide - Module organization, dependencies — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - #### 2.2 Implement Core Infrastructure — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Create shared utilities: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - API client with authentication — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Error handling helpers — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Response formatting (JSON/Markdown) — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - #### 2.3 Implement Tools — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Use Zod (TypeScript) or Pydantic (Python) — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Include constraints and clear descriptions — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Add examples in field descriptions — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Define outputSchema where possible for structured data — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Use structuredContent in tool responses (TypeScript SDK feature) — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Helps clients understand and process tool outputs — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Tool Description: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Concise summary of functionality — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Parameter descriptions — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Async/await for I/O operations — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Proper error handling with actionable messages — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Support pagination where applicable — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - Return both text content and structured data when using modern SDKs — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - readOnlyHint: true/false — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - destructiveHint: true/false — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - idempotentHint: true/false — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) - openWorldHint: true/false — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-2-implementation) ## Phase 3: Review and Test - #### 3.1 Code Quality — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) - No duplicated code (DRY principle) — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) - Consistent error handling — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) - Clear tool descriptions — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) - #### 3.2 Build and Test — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) - Run npm run build to verify compilation — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) - Test with MCP Inspector: npx @modelcontextprotocol/inspector — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) - Verify syntax: python -m py_compile your_server.py — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) - Test with MCP Inspector — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) - See language-specific guides for detailed testing approaches and quality checklists. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-3-review-and-test) ## Phase 4: Create Evaluations - After implementing your MCP server, create comprehensive evaluations to test its effectiveness. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Load ✅ Evaluation Guide for complete evaluation guidelines. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - #### 4.1 Understand Evaluation Purpose — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Use evaluations to test whether LLMs can effectively use your MCP server to answer realistic, complex questions. — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - #### 4.2 Create 10 Evaluation Questions — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - To create effective evaluations, follow the process outlined in the evaluation guide: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Tool Inspection: List available tools and understand their capabilities — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Content Exploration: Use READ-ONLY operations to explore available data — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Question Generation: Create 10 complex, realistic questions — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Answer Verification: Solve each question yourself to verify answers — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - #### 4.3 Evaluation Requirements — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Ensure each question is: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Independent: Not dependent on other questions — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Read-only: Only non-destructive operations required — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Complex: Requiring multiple tool calls and deep exploration — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Realistic: Based on real use cases humans would care about — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Verifiable: Single, clear answer that can be verified by string comparison — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Stable: Answer won't change over time — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - #### 4.4 Output Format — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) - Create an XML file with this structure: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#phase-4-create-evaluations) ## 📚 Documentation Library - Load these resources as needed during development: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#-documentation-library) ## Core MCP Documentation (Load First) - MCP Protocol: Start with sitemap at https://modelcontextprotocol.io/sitemap.xml, then fetch specific pages with .md suffix — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#core-mcp-documentation-load-first) - 📋 MCP Best Practices - Universal MCP guidelines including: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#core-mcp-documentation-load-first) - Server and tool naming conventions — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#core-mcp-documentation-load-first) - Response format guidelines (JSON vs Markdown) — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#core-mcp-documentation-load-first) - Pagination best practices — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#core-mcp-documentation-load-first) - Transport selection (streamable HTTP vs stdio) — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#core-mcp-documentation-load-first) - Security and error handling standards — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#core-mcp-documentation-load-first) ## SDK Documentation (Load During Phase 1/2) - Python SDK: Fetch from https://raw.githubusercontent.com/modelcontextprotocol/python-sdk/main/README.md — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#sdk-documentation-load-during-phase-12) - TypeScript SDK: Fetch from https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/main/README.md — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#sdk-documentation-load-during-phase-12) ## Language-Specific Implementation Guides (Load During Phase 2) - 🐍 Python Implementation Guide - Complete Python/FastMCP guide with: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#language-specific-implementation-guides-load-during-phase-2) - Server initialization patterns — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#language-specific-implementation-guides-load-during-phase-2) - Pydantic model examples — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#language-specific-implementation-guides-load-during-phase-2) - Tool registration with @mcp.tool — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#language-specific-implementation-guides-load-during-phase-2) - Complete working examples — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#language-specific-implementation-guides-load-during-phase-2) - ⚡ TypeScript Implementation Guide - Complete TypeScript guide with: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#language-specific-implementation-guides-load-during-phase-2) - Tool registration with server.registerTool — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#language-specific-implementation-guides-load-during-phase-2) ## Evaluation Guide (Load During Phase 4) - ✅ Evaluation Guide - Complete evaluation creation guide with: — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#evaluation-guide-load-during-phase-4) - Question creation guidelines — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#evaluation-guide-load-during-phase-4) - Answer verification strategies — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#evaluation-guide-load-during-phase-4) - XML format specifications — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#evaluation-guide-load-during-phase-4) - Example questions and answers — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#evaluation-guide-load-during-phase-4) - Running an evaluation with the provided scripts — [source](https://llms-explorer.com/sources/mdb-context-hub/mcp-builder/#evaluation-guide-load-during-phase-4) ## Where this helps - Designing the tool surface for a new MCP server, deciding whether to expose broad API-coverage tools or a smaller set of purpose-built workflow tools for the tasks agents actually need. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Naming and documenting tools so an LLM client can reliably discover and pick the right one, especially once a server exposes more than a handful of tools. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Deciding when to build a new MCP server versus wrapping an existing API directly, following the pack's four-phase workflow of research/planning, implementation, review/test, and evaluation. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Standing up evaluation infrastructure for an MCP server before shipping it, to verify LLMs can actually use the exposed tools to answer realistic, complex questions rather than just execute without error. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* ## Project ideas - Build an MCP server with a small set of workflow-oriented tools, rather than one-to-one API wrappers, for a task domain you use often, and give each tool a consistent naming prefix such as `service_verb_noun`. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Build an evaluation suite for an MCP server following the pack's Phase 4 guidance — realistic question generation, XML-format answer verification, and a scored pass/fail per question. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Build a Python (FastMCP) or TypeScript MCP server from the pack's referenced SDK docs, following its recommended project-structure conventions. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Build a response-shaping layer for an existing MCP server's tools that trims and paginates results, since the pack flags context management — concise descriptions, filterable/paginated output — as a design concern. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* ## Antipatterns - Building one MCP tool per raw API endpoint by default instead of considering purpose-built workflow tools — comprehensive coverage without curation can leave an agent unable to tell which tool actually fits a task. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Shipping an MCP server without the Phase 4 evaluation step — code-quality review alone (DRY, consistent error handling) doesn't tell you whether an LLM can actually use the server to complete real tasks. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Giving tools inconsistent or generic names instead of a consistent prefix convention, which is exactly what the pack's discoverability guidance (e.g., github_create_issue, github_list_repos) is meant to prevent. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Skipping Phase 1 research — reading the current MCP protocol docs and SDK README before building — and working from stale or assumed knowledge of the protocol instead. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* ## Known issues - This pack is itself a workflow/routing document — it points to external docs (protocol sitemap, SDK READMEs, best-practices guide) rather than containing the implementation details itself, so building a server still requires fetching those linked resources. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - Balancing API coverage against workflow-tool curation is presented as a judgment call, not a formula — the pack gives no hard rule for when a server has too many or too few tools. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* - The pack's evaluation guidance (XML-format answer verification, question-creation guidelines) implies real engineering effort beyond writing the server itself, which teams building MCP servers under time pressure often skip. — [source](https://llms-explorer.com/tree/mcp-server-builder-patterns/) *(AI-suggested, synthesized from this pack's existing facts — not extracted from a source document.)* ## Context files - [MCP Server Builder Patterns](https://llms-explorer.com/downloads/sources/mdb-context-hub/mcp-builder.md)