I see a good number of comments that seem skeptical or confused about what's going on here or what the value is.
One thing that some people may not realize is that right now there's a MASSIVE amount of effort duplication around developing something that could maybe end up looking like MCP. Everyone building an LLM agent (or pseudo-agent, or whatever) right now is writing a bunch of boilerplate for mapping between message formats, tool specification formats, prompt templating, etc.
Now, having said that, I do feel a little bit like there's a few mistakes being made by Anthropic here. The big one to me is that it seems like they've set the scope too big. For example, why are they shipping standalone clients and servers rather than client/server libraries for all the existing and wildly popular ways to fetch and serve HTTP? When I've seen similar mistakes made (e.g. by LangChain), I assume they're targeting brand new developers who don't realize that they just want to make some HTTP calls.
Another thing that I think adds to the confusion is that, while the boilerplate-ish stuff I mentioned above is annoying, what's REALLY annoying and actually hard is generating a series of contexts using variations of similar prompts in response to errors/anomalies/features detected in generated text. IMO this is how I define "prompt engineering" and it's the actual hard problem we have to solve. By naming the protocol the Model Context Protocol, I assumed they were solving prompt engineering problems (maybe by standardizing common prompting techniques like ReAct, CoT, etc).