@jlowin.dev.bsky.social
CEO @prefect.io. Building FastMCP. Mostly harmless.
It's hard to overstate what Prefect 3 did for adoption. Usage has now increased nearly 10x since GA less than a year ago... and the rate is accelerating.
01.08.2025 12:53 — 👍 6 🔁 1 💬 0 📌 0I'll believe in AGI when my iPhone can filter out political spam text messages. But not before.
28.07.2025 15:09 — 👍 6 🔁 1 💬 1 📌 12018 AI demo: book a reservation
2019 AI demo: book a reservation
2020 AI demo: book a reservation
2021 AI demo: book a reservation
2022 AI demo: book a reservation
2023 AI demo: book a reservation
2024 AI demo: book a reservation
2025 AI demo: book a reservation with agents
There's still a massive gap between research and reality. If you can look past the shiny social media demos, pragmatic teams are actually shipping true AI-native innovations. Every empirical friction they encounter is a chance for us to learn and improve core infrastructure like FastMCP.
18.07.2025 23:40 — 👍 1 🔁 0 💬 0 📌 0
I was honored to open PayPal's first-ever AI Summit!
Watching a company at this scale commit to radical transformation is astounding and inspiring, and I got to see this not only from the keynote stage but in hours of conversations with the AI, LLM, and MCP teams after.
🤩 Customer momentum: +70 % net growth in just six months.
📈 Exploding usage: Prefect and FastMCP are both seeing record growth.
None of this happens without an extraordinary team. Can’t wait to celebrate at our annual all-hands in two weeks, then roll up our sleeves for @prefect.io’s next chapter.
Thrilled to share four milestones we hit in July:
🚀 Record‑breaking quarter: we just posted the strongest in company history.
🏁 Profitable: we’ll affirm this milestone in the next few weeks.
I almost didn’t make cyclopts a fastmcp dependency because it didn’t have a lot of downloads.
Problem solved, I guess?
2024: No wifi on the flight? Guess I'll do some coding
2025: No wifi on the flight? Guess I can't do any coding.
🛑 Stop converting your REST APIs to MCP.
I know that slick OpenAPI-to-MCP converter feels like magic, but it's poisoning your agent. I'm telling you this as the person who built the most popular one.
Here’s why we need to rethink agent-first API design:
www.jlowin.dev/blog/stop-co...
“Two months ago we launched self-serve pricing at @prefect.io. Today is Tuesday and it's already our 3rd largest week of sign-ups ever 📈”
- @cicdw.dev
www.linkedin.com/posts/whitec...
It's all fun and games until an AI vibe-codes a 42,000 line PR and another AI vibe-reviews it as "impressive and substantial."
This is the way the world ends, not with a bang but a "LGTM!"
github.com/google-gemin...
Sure, I could use AI video to sell something... or I could just sit here and watch the virtual starling murmurations fly by
07.07.2025 18:38 — 👍 5 🔁 0 💬 1 📌 0
Git worktrees are the recommended way to run Claude Code in parallel, but managing them is kind of tedious... so I built claude-wt!
A simple utility to spin up and manage Claude in isolated worktrees.
No install needed: uvx claude-wt new
"Cyclopts is what you thought Typer was."
Just refactored the FastMCP CLI and I have to say I agree with this line from the Cyclopts docs.
“Not just X, but Y” is the tell nobody seems to be filtering out…
25.06.2025 14:41 — 👍 3 🔁 0 💬 0 📌 0
We're big fans of @mintlify but there's no great way to create Python SDK docs automatically.
Until now!
@alternatebuild.dev created mdxify to automatically generate beautiful docs from code, and it works great. Check out gofastmcp.com/python-sdk and docs.prefect.io/v3/api-ref/p... to see!
In theory maybe no but as long as per-token pricing is a thing it will matter. Look what lengths we go to to shave microseconds off CPU-billed processes!
24.06.2025 20:29 — 👍 1 🔁 0 💬 0 📌 0I think context pollution is the single biggest problem in the AI space today (more on that soon) and larger contexts will be disproportionately filled by extraneous information than used to filter that info.
24.06.2025 16:50 — 👍 3 🔁 0 💬 2 📌 0
A common question I hear when teams start building for AI is, “Why can’t agents just use our REST API instead of MCP?”
My response is usually the same: “Why can’t you just use your REST API instead of a UI?”
www.jlowin.dev/blog/curatio...
@alternatebuild.dev wrote up his journey to build an atproto (Bluesky) MCP server, including all the code you need to let your AI post!
Lots of interesting details on optimizing the API design.
blog.alternatebuild.dev/an-atproto-m...
Me too
23.06.2025 23:06 — 👍 1 🔁 0 💬 0 📌 0oh nice, i’ve been wanting this
23.06.2025 23:00 — 👍 13 🔁 1 💬 2 📌 0
Introducing MCP-native middleware, as easy as 1-2-FastMCP.
With FastMCP 2.9, you can now add cross-cutting logic like auth and logging with high-level hooks that understand your tools and resources.
See how it works: www.jlowin.dev/blog/fastmcp...
Elicitation is a new MCP feature that I'm really excited about.
When Claude Code asks you "do you want to create this file? yes / no / no and tell Claude why", that's elicitation. It lets programmatic actions reach back into natural-language-land to get 👍/👎 approvals or details.
In FastMCP soon!
In this economy?
22.06.2025 21:15 — 👍 3 🔁 0 💬 0 📌 0If you ask Claude Code to read any of the OpenAI docs it hits a 403.
🤷♂️
This is succinct and well written. As backend engineers we are now designing APIs for humans, software, and agents. Different concerns for different clients.
22.06.2025 15:43 — 👍 4 🔁 1 💬 0 📌 0
For years, we've designed APIs for maximum discoverability. The more features a developer can find, the better.
In an agentic world, that entire philosophy is a liability. The best API for an agent is the one it can't see.
Even more on designing products for agents: www.jlowin.dev/blog/curatio...
As the author of FastMCP, it might seem strange that I haven’t prioritized an MCP server for Prefect. But honestly, the user story for “chatting with your orchestrator” has always felt weak.
It turns out I was thinking about the wrong user.
www.jlowin.dev/blog/as-an-a...
