MCP Builder

Create MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools.

High-Level Workflow

Phase 1: Deep Research and Planning

Understand Modern MCP Design

API Coverage vs. Workflow Tools: Balance comprehensive API endpoint coverage with specialized workflow tools. When uncertain, prioritize comprehensive API coverage.

Tool Naming and Discoverability: Clear, descriptive tool names help agents find the right tools quickly. Use consistent prefixes and action-oriented naming.

Context Management: Agents benefit from concise tool descriptions and the ability to filter/paginate results.

Actionable Error Messages: Error messages should guide agents toward solutions with specific suggestions and next steps.

Study MCP Protocol Documentation

Navigate the MCP specification starting with the sitemap: https://modelcontextprotocol.io/sitemap.xml

Key pages to review:

• Specification overview and architecture
• Transport mechanisms (streamable HTTP, stdio)
• Tool, resource, and prompt definitions

Plan Your Implementation

Recommended stack:

• Language: TypeScript (high-quality SDK support)
• Transport: Streamable HTTP for remote servers, stdio for local servers

Phase 2: Implementation

Set Up Project Structure

• TypeScript project with proper tsconfig.json
• Zod schemas for input validation
• Proper error handling

Implement Core Infrastructure

Create shared utilities:

• API client with authentication
• Error handling helpers
• Response formatting (JSON/Markdown)
• Pagination support

Implement Tools

For each tool:

• Input Schema: Use Zod with constraints and clear descriptions
• Output Schema: Define outputSchema where possible
• Tool Description: Concise summary of functionality
• Implementation: Async/await, proper error handling, pagination support
• Annotations: readOnlyHint, destructiveHint, idempotentHint, openWorldHint

Phase 3: Review and Test

Code Quality

Review for:

• No duplicated code (DRY principle)
• Consistent error handling
• Full type coverage
• Clear tool descriptions

Build and Test

npm run build
npx @modelcontextprotocol/inspector

Phase 4: Create Evaluations

Create comprehensive evaluations to test effectiveness:

1. Tool Inspection: List available tools
2. Content Exploration: Use READ-ONLY operations
3. Question Generation: Create 10 complex, realistic questions
4. Answer Verification: Solve each question yourself

Each question must be:

• Independent
• Read-only
• Complex (requiring multiple tool calls)
• Realistic
• Verifiable
• Stable