Depends on what tool you use. As an example for github gh is way more efficient than using the github MCP because the training data of LLM actually contains gh documentation and how to use it.
However, if you have a very niche command tool or a work related internal tool, LLM has no idea on how to use it and it could waste a lot of tokens by trying to figure out what works and what doesn't and how to use it in every session. That's where MCP comes in handy. LLMs are trained to use the MCP protocol and it can efficiently figure out which tool to be called and how to process the output when a niche command tool is exposed via an MCP.
However, if you have a very niche command tool or a work related internal tool, LLM has no idea on how to use it and it could waste a lot of tokens by trying to figure out what works and what doesn't and how to use it in every session. That's where MCP comes in handy. LLMs are trained to use the MCP protocol and it can efficiently figure out which tool to be called and how to process the output when a niche command tool is exposed via an MCP.