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CLAUDE.md vs SKILL.md vs MCP: The Modern Agent Stack Explained
Stop pasting everything into one file. Learn how to separate always-on rules, task runbooks, and live tools.
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Most people building with Claude Code and early users of AI coding agents make the same mistake in their first month. They open CLAUDE.md, start typing everything they can think of into it, and keep going until the file is 600–900 lines long. Coding style guides, deployment steps, code review checklists, and raw database schemas dumped straight into one file.
They assume that giving the agent as much context as possible upfront would make it smarter. Instead, it choke the agent’s working memory. As a result the coding agent starts acting weird and gives not so accurate responses. Prompts that used to work earlier, now stop working. Something feels off, and it’s hard to say exactly what.
On every simple prompt, the model has to parse hundreds of lines of irrelevant instructions before looking at a single line of code. The problem is neither the model, nor bad prompting. The mistake was trying to make one text file do three different jobs.
Modern coding agents like Claude Code work best when you split your instructions into three clean parts: always-on project rules, on-demand task skills, and live tool connections via MCP. When you keep these parts separate, the model gets only the information it needs, right…
