๐๐ก๐๐ญ ๐ข๐ญ ๐ญ๐๐ค๐๐ฌ ๐ญ๐จ ๐๐ฎ๐ข๐ฅ๐ ๐ ๐ฉ๐ซ๐จ๐๐ฎ๐๐ญ๐ข๐จ๐ง-๐ ๐ซ๐๐๐ ๐๐๐ ๐ฌ๐๐ซ๐ฏ๐๐ซ
My notes from exploring how to design, build, and test a production-grade MCP server using open-source Python tools.
Iโve been looking into how to build a full-featured MCP serverโstarting with the official MCP site and then digging into a few open projects and examples.
Two simple questions are driving this:
โ What are the main pieces needed to build a production-grade MCP server?
โ What open-source tools can I use locally (no cloud setup) to build each piece in a simple and testable way?
What Iโve figured out so far:
Below are the main parts of the system and the tools I started exploring:
โ Accept and route incoming HTTP requests
Use a lightweight web framework like ๐ ๐๐ฌ๐ญ๐๐๐ (used internally by ๐ ๐๐ฌ๐ญ๐๐๐) to expose the MCP server over Streamable HTTP or SSE.
โก Parse and validate the JSON request payload
Use ๐๐ฒ๐๐๐ง๐ญ๐ข๐ (via FastMCP) to convert JSON input into clean, type-checked Python objects.
โข Verify the identity of the caller
Use ๐๐ฒ๐๐๐ to decode and validate JSON Web Tokens (JWTs) that prove who the client is.
โฃ Check what the caller is allowed to do
Use ๐ ๐๐ฌ๐ญ๐๐๐'๐ฌ Depends system to apply role-based access control for each request.
โค Enforce request limits per user
Use ๐ฌ๐ฅ๐จ๐ฐ๐๐ฉ๐ข to add rate-limiting middleware so users canโt overload the server.
โฅ Validate tool input before execution
Let ๐๐ฒ๐๐๐ง๐ญ๐ข๐ (automatically used by FastMCP) validate input arguments before calling the tool.
โฆ Look up the requested tool by name
Use FastMCPโs @mcp.tool() decorator to register callable tools.
(You can also use @mcp.resource() for shared resources and @mcp.prom() for prompt templates.)
โง Run the tool logic
FastMCP handles calling the right tool function, passing input, and handling any exceptions.
โจ Format the tool output into a standard response
Use ๐๐๐๐-๐๐๐, which FastMCP handles under the hood, to return either the result or a structured error.
โฉ Send the response back to the client
Use built-in HTTP support or Server-Sent Events (SSE) in FastAPI/FastMCP to return the response.
I havenโt put everything together yet, but Iโve started.
Iโll keep sharing what I learn as I goโhoping to eventually have a full, working MCP server built from scratch using these tools.