MCP Server Builder Guide

Problem: MCP Tools Can Become Endpoint Dumps

The difficulty of an MCP server is not registering a few tools, but whether an LLM can use them to complete real tasks reliably. Common failures include vague tool names, unclear descriptions, over-broad responses, and error messages that do not guide the next action, causing agents to guess or repeat calls.

How It Works

mcp-builder provides a staged workflow for server development:

• Research and planning: Review MCP specs, SDK docs, and target APIs; decide tool granularity, naming prefixes, transport, and data models.
• Implementation: Build the project structure, add auth clients, error handling, response formatting, and pagination, then define input and output schemas with Zod or Pydantic, including hints such as readOnlyHint and destructiveHint.
• Review and testing: Check duplicated code, consistent error handling, and type coverage, then run builds and validate behavior with MCP Inspector.
• Evaluation: Generate 10 independent, read-only, complex, and verifiable questions to test whether an LLM can combine tools correctly for realistic scenarios.

Limits

This skill fits developing MCP servers for external services, especially TypeScript or Python implementations over remote streamable HTTP or local stdio. It does not provide business API logic, so target service docs, credentials, and test data are still required. For write-heavy, stateful, or permission-sensitive tools, pay close attention to error recovery, idempotency, and destructive-action hints.