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Building MCP servers in the real world

By Gergely Orosz · The Pragmatic Engineer · · 20 min read

Deep Dives

Explore related topics with these Wikipedia articles, rewritten for enjoyable reading:

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The Model Context Protocol (MCP) was released almost exactly a year ago by Anthropic, and today, MCP is enjoying quite a moment, with strong growth in the numbers of devs building MCP servers. That might be related to MCP servers being a great way to give agents like Claude Code, Cursor Agent, and other LLMs new capabilities to use services, query documentation, and be more efficient. Adoption is widespread and diverse, across cutting-edge startups and regulated industries like aerospace alike.

One year on, how are engineering teams using this technology, and what does that teach us? To find out, we collected input from 46 software engineers who build and use MCP servers at work, and talked with Jeremiah Lowin, CEO of Prefect and creator of FastMCP, the leading MCP framework for Python, and Den Delimarsky, core MCP maintainer and Principal Engineer at Microsoft.

Thanks to everyone who shared their experience of building with MCP.

Today, we cover:

  1. MCP fundamentals. Brief recap of the protocol.

  2. Usage realities. Internal MCP server usage outpaces its public usage, business stakeholders are heavy MCP users, and other details.

  3. How teams use MCP. Based on a dozen use cases, there are varied ways of using it.

  4. Popular public MCP servers. Stats from widely-used public MCP servers operated by Sentry and Linear, plus an odd conjunction of thousands of DAUs and millions of daily sessions.

  5. Security considerations. Security’s still the Achilles heel of MCPs and LLMs. There are some sensible security practices for treading carefully in the space.

  6. Learnings from building MCPs. Start small and local, choose the development language carefully, design primitives for agents and not humans – & more.

  7. Useful tools for building MCP servers. FastMCP, MCP Inspector, and Cloudflare’s remote MCP guide among the top mentions.

Our look into MCP usage suggests that using, building, and maintaining MCP servers are on the way to becoming part of the software engineering toolset; perhaps they already are. Meantime, best practices are still taking shape. Let’s get into it:

1. MCP fundamentals

The MCP protocol was released in November 2024 and was developed by two software engineers at Anthropic, David Soria Parra, and Justin Spahr-Summers, who started work on it that July.

The protocol aims to be the “USB-C” layer for AI applications. It’s a standardized protocol to connect Clients (chatbots, IDEs, AI applications) to Servers (data, files, and tools). Here’s how the protocol works, ...

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