CLIs are great for some applications! But 'progressive disclosure' means more mistakes to be corrected and more round trips to the model - every time[1] you use the tool in a new thread. You're trading latency for lower cost/more free context. That might be great! But it might not be, and the opposite trade (more money/less context for lower latency) makes a lot of sense for some applications. esp. if the 'more money' part can be amortized over lots of users by keeping the tool definitions block cached.
[1]: one might say 'of course you can just add details about the CLI to the prompt' ... which reinvents MCP in an ad hoc underspecified non-portable mode in your prompt.
[1]: one might say 'of course you can just add details about the CLI to the prompt' ... which reinvents MCP in an ad hoc underspecified non-portable mode in your prompt.