mcp-server-development

Build an MCP server by initializing a TypeScript project, creating handler classes for each tool, validating inputs with Zod schemas, and wiring handlers into a central index. Use Content-Length framing for transport and JSON-RPC patterns for request-response cycles.

The handler-based pattern creates one class per tool, each implementing a base handler contract. This design isolates tool logic, simplifies testing, and enforces consistent input validation and error handling across your MCP server.

Define Zod schemas for each tool's input parameters, then validate requests in your handler before processing. Zod ensures type safety and generates MCP-compliant error responses when validation fails.

Implement structured error handling using MCP error codes and JSON-RPC response patterns. Wrap handlers to catch exceptions, map them to appropriate MCP codes, and return properly formatted error objects to the client.

Use contract tests to verify handler compliance with the base handler interface, mocks to isolate tool logic, and integration tests to validate JSON-RPC framing and Content-Length transport end-to-end.

Yes, MCP transport uses Content-Length framing and NDJSON format for reliability. This ensures messages are properly delimited and compatible with streaming I/O and bidirectional communication.