Better if you see it for yourself. Setup GitHub MCP and enable all tools. It will start using wrong tools at wrong time, overuse it. Add languageserver-mcp, and it suddenly will start trying to use it for file edits and create a huge mess in files.

I have nixos mcp server available to search documentation and packages, but it often starts using it for entirely different things.

It's almost like when you tell someone not to think about an elephant, and they can't stop thinking - if you provide it with a tool, it will try to use it. That's why sub-agents are better because you can limit tool availability.

I use tidewave mcp and as soon as it uses a single tool from it, claude becomes obsessed with it, I saw it waste entire context running evals there without doing any file edits.