silliness

MCP protocol of choice: stdin/stdout? WTF, man?

Gregory Golberg projects, self-promotion, silliness, voitta, yak shaving , , , , , , , ,

Let’s talk about MCP. More specifically, let’s talk about using stdin/stdout as a protocol transport layer in the year of our Lord 2025.

Yes, yes—it’s universal. It’s composable. It works “everywhere.” It’s the spiritual successor to Unix pipes, which were cool at the time. The time when my Dad was hitting on my Mom. As an actual transport layer, stdin/stdout is a disaster.

Debugging Is Basically a Crime

Let’s say I want to create an MCP server in Python. Reasonable. Now let’s say I want to debug it. Set a breakpoint. Inspect variables. Use threads. Maybe spin up the LLM in the same process for context. You know, software engineering.

The moment you try to do this, you’re writing a debug driver. Congratulations. You are now:

  • Building a fake client to simulate a streaming LLM
  • Implementing bidirectional IO while praying the LLM doesn’t send surprise newline characters
  • Wrapping things in threads and/or asyncio or multiprocessing or whatnot other total fucking bullshit.

Been there. Twice:

  • Voitta’s Brokkoly: Thought I could run the LLM and the driver in one process. Spent 3 hours implementing queues, got it half-working, and realized I was debugging my own debug tool.
  • Samtyzukki: Round two. Same problem. Ended up with more abstraction layers than a Kafka conference.

Eventually, I just gave up and decided to use SSE (Server-Sent Events). Because you know what’s great about SSE? You can log things. You can see the messages. You can debug. It’s like rediscovering civilization after weeks of wilderness survival with only printf() and trauma.

 stdout Is Sacred, Until It Isn’t

Here’s the other problem. stdout is a shared space. You can’t count on it. Libraries will write to it. Dependencies will write to it. Your logger will write to it. Some genius upstream will write:

print(“INFO: falling back to CPU because the GPU is feeling shy today.”)

Congratulations. You just corrupted your transport. Your parser reads that as malformed JSON or a broken packet or an existential and spiritual crisis.

It’s not a bug. It’s a design decision—and not a good one.

This is the part where I invoke Rob Pike. Sorry. Not sorry.

In Go, to format a date, one doesn’t simply use YYYY-MM-DD. You do Mon Jan 2 15:04:05 MST 2006.

Because, I get it, we all need to get high once in a while. But srsly.

Some more random notes

Gregory Golberg holding forth, silliness , , , , , ,
  • Completely agree with @mipsytipsy here:

    I am an extremely literal person, and literally speaking, nobody can be a “full stack” engineer. The idea is a ridiculous one. There’s too much stack! But that’s not what people mean when they say it. They mean, “I’m not just a frontend or backend engineer. I span boundaries.”
  • Yeah, this blog is for bragging.
  • What is it with fillable PDFs on some gov’t websites (I know, I know; that’s a post for a different day) — but they can be sometimes saved but not printable?
  • TFW about 16 years later after your colleague writes an impassioned call to “Tear down that GIL!” (take that, Mr. Gorbachev!), the GIL is finally torn down.
  • I was wondering what the Go team was smoking when they came up with the reference date concept and can I have some of that?
  • What is it that causes Medium to suck so much? Is it all the useless “content creators” writing things pre-GPT that just rephrase stuff from the Internet with nary a value added (“Here’s 10 reasons to learn Python”, and here’s how to write “Hello, world” in C, did you know?)? Is it that now probably thousands more are using generative AI — kinda indistinguishable? Or is it their idiotic subscription model which cannot deal with some logins? (I should really devote time to figure out that one but why — is that platform really worth anything at all?)