Unable to run the hello-world-mcp-server example

[m5p3nc3r]

Describe the bug
When trying to launch hello-world-mcp-server using npx -y @modelcontextprotocol/inspector ./target/release/hello-world-mcp-server, I am unable to connect to the server

I get an error message in the inspector saying 'Server started successfully', so to me it looks like a protocol error between the server and the inspector?

What are you using rust-mcp-sdk for?
Select all that apply:

• Developing a MCP Server
• Developing a MCP Client

Technical details:

• rust-mcp-sdk Version : .0.4.7
• Cargo features enabled for rust-mcp-sdk : "server","macros","hyper-server","ssl","2025_03_26"
• Environment/OS (Mac, Linux, Windows, etc) : WSL2 (Ubuntu 24.04)

To Reproduce
Steps to reproduce the behavior:

1. Download the git repo @ 42292f9
2. Follow the instructions in the example readme.

Expected behavior
I can connect to the server and exercise the available tools

Screenshots

Additional context
The terminal output when attempting to connect to the server is:

New STDIO connection request
Query parameters: {"command":"./target/release/hello-world-mcp-server","args":"","env":"{\"HOME\":\"/home/matt\",\"LOGNAME\":\"matt\",\"PATH\":__REDACTED__,\"SHELL\":\"/bin/bash\",\"TERM\":\"xterm-256color\",\"USER\":\"matt\"}","transportType":"stdio"}
STDIO transport: command=./target/release/hello-world-mcp-server, args=
Created server transport
Created client transport
Received POST message for sessionId 637b4e8c-738d-4912-a8fe-ccc87d385b29

[Vaiz]

I noticed the same problem with MCP Inspector after recent update.
But other tools works fine, e.g. MCP Discovery or VS Code Copilot.

[hashemix]

Thanks for reporting this @m5p3nc3r .

As @Vaiz mentioned that is because of the latest MCP Inspector update that is mandating MCP protocol 2025_06_18 and rust-mcp-sdk does not support it currently.

While 2025_06_18 support is on its way , you can use previous version of MCP Inspector (v 0.14.3):

npx -y @modelcontextprotocol/inspector@0.14.3 ./target/release/hello-world-mcp-server

related issue: #68

[m5p3nc3r]

Hey @hashemix, thanks for the info. Using the older inspector worked fine for me.

Out of interest, I can see that rust-mcp-schema already supports 2025_06_18, so how long does it normally take for this downstream project to adopt the latest specification? Also - is there anything I can do to help?

[hashemix]

Out of interest, I can see that rust-mcp-schema already supports 2025_06_18, so how long does it normally take for this downstream project to adopt the latest specification?

That one was a little tricky, I had to update rust-mcp-macro and put some extra effort to make sure sdk remains compatible with previous protocol version.

It's nearly complete and working on my end, just needs a few final touches. I plan to release it before the weekend, as I’ve been working on it during my free time after work, luckily today was a holiday and I made some good progress.

Also - is there anything I can do to help?

Thanks, appreciate the offer ❤. No help needed for the 2025_06_18 support right now, but if there’s anything else you’d like to contribute to or explore, feel free to jump in! I’m always open to collaboration on new features, improving test coverage , bug fixes, or improving documentation.