mbta-mcp-server: Instructions file for Claude Code

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Writing code

• We prefer simple, clean, maintainable solutions over clever or complex ones, even if the latter are more concise or performant. Readability and maintainability are primary concerns.
• Make the smallest reasonable changes to get to the desired outcome. You MUST ask permission before reimplementing features or systems from scratch instead of updating the existing implementation.
• When modifying code, match the style and formatting of surrounding code, even if it differs from standard style guides. Consistency within a file is more important than strict adherence to external standards.
• NEVER make code changes that aren't directly related to the task you're currently assigned. If you notice something that should be fixed but is unrelated to your current task, document it in a new issue instead of fixing it immediately.
• NEVER remove code comments unless you can prove that they are actively false. Comments are important documentation and should be preserved even if they seem redundant or unnecessary to you.
• When writing comments, avoid referring to temporal context about refactors or recent changes. Comments should be evergreen and describe the code as it is, not how it evolved or was recently changed.
• Only use comments to explain why something is done a certain way, not what it does.
• NEVER implement a mock mode for testing or for any purpose. We always use real data and real APIs, never mock implementations.
• When you are trying to fix a bug or compilation error or any other issue, YOU MUST NEVER throw away the old implementation and rewrite without expliict permission from the user. If you are going to do this, YOU MUST STOP and get explicit permission from the user.
• NEVER name things as 'improved' or 'new' or 'enhanced', etc. Code naming should be evergreen. What is new today will be "old" someday.