MCP Server using STDIO - Attempting to user JSON RPC from Windows command line with partial success

[jayhamilton]

Bug description
Created an MCP server. Added it to VSCode. The server is recognized and the 3 tools defined appear and work. On occasion, the 1 defined resource may appear in one of the VSCode windows but more times than not, selecting the resource results in a VS Code window showing an indeterminate progress bar until I restart VSCode.

What I would like to do is test the MCP server using JSON RPC. Here are the commands I sent using PowerShell and the results. It seems the only successful command that works is the initialization command. Not sure if the way I am attempting to test this is valid. resource or tool list command will return an error if the syntax is wrong, but will not display information when it is correct

echo '{"jsonrpc":"2.0", "id":1, "method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{"roots":{"listChanged":true}, "sampling":{}}, "clientInfo":{"name":"test-client","version":"1.0.0"}}}' | java -jar mcp-server-0.0.1-SNAPSHOT.jar
:::::::::{"jsonrpc":"2.0","id":1,"result":{"protocolVersion":"2024-11-05","capabilities":{"completions":{},"logging":{},"prompts":{"listChanged":true},"resources":{"subscribe":false,"listChanged":true},"tools":{"listChanged":true}},"serverInfo":{"name":"sds-mcp-server","version":"1.0.0"}}}
:
echo '{"jsonrpc":"2.0", "id":1, "method":"list/tools","params":{}}' | java -jar mcp-server-0.0.1-SNAPSHOT.jar
::::::::{"jsonrpc":"2.0","id":1,"error":{"code":-32601,"message":"Method not found: list/tools"}}
:
echo '{"jsonrpc":"2.0", "id":1, "method":"tools/list","params":{}}' | java -jar mcp-server-0.0.1-SNAPSHOT.jar
:::::::::
echo '{"jsonrpc":"2.0", "id":1, "method":"tools/resources","params":{}}' | java -jar mcp-server-0.0.1-SNAPSHOT.jar
::::::::{"jsonrpc":"2.0","id":1,"error":{"code":-32601,"message":"Method not found: tools/resources"}}
:
echo '{"jsonrpc":"2.0", "id":1, "method":"list/resources","params":{}}' | java -jar mcp-server-0.0.1-SNAPSHOT.jar
::::::::{"jsonrpc":"2.0","id":1,"error":{"code":-32601,"message":"Method not found: list/resources"}}
:
echo '{"jsonrpc":"2.0", "id":1, "method":"resources/list","params":{}}' | java -jar mcp-server-0.0.1-SNAPSHOT.jar
:::::::::

Environment
Windows 11
properties file
spring.application.name=mcp-server

spring.ai.mcp.server.type=SYNC
spring.ai.mcp.server.name=my-mcp-server
spring.ai.mcp.server.version=1.0.0

spring.ai.mcp.server.stdio=true
spring.main.web-application-type=none
spring.main.banner-mode=off
logging.pattern.console=:
logging.file.name=./log/mcp-server.log

Steps to reproduce
Build the MCP server with a few tools and a resource
Run JSON RPC commands from the command line

Expected behavior
Could be developer error here

Minimal Complete Reproducible example
Example above

[wilocu]

I have a couple of questions.
Exact JSON commands you're using for testing:
- What's your tools/list request format?
- What's your resources/list request format?
Response details:
- Are you getting HTTP errors, empty responses, or JSON parsing errors?
- Any error messages in your server logs?
Testing method:
- How are you sending the JSON RPC commands? (curl, Postman, CLI pipe, etc.)
- Are you using STDIO or HTTP transport?

[jayhamilton]

I am using the echo command to pass a JSON string to the SpringBoot MCP server. I am using STDIO and sending commands using a pipe, not using http.

JSONRPC MCP initialize request:

echo '{"jsonrpc":"2.0", "id":1, "method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{"roots":{"listChanged":true}, "sampling":{}}, "clientInfo":{"name":"test-client","version":"1.0.0"}}}' | java -jar mcp-server-0.0.1-SNAPSHOT.jar

JSONRPC MCP successful initialize response:

:::::::::{"jsonrpc":"2.0","id":1,"result":{"protocolVersion":"2024-11-05","capabilities":{"completions":{},"logging":{},"prompts":{"listChanged":true},"resources":{"subscribe":false,"listChanged":true},"tools":{"listChanged":true}},"serverInfo":{"name":"sds-mcp-server","version":"1.0.0"}}}

tools/list request:

echo '{"jsonrpc":"2.0", "id":1, "method":"tools/list","params":{}}' | java -jar mcp-server-0.0.1-SNAPSHOT.jar

Empty tools/list response:
:::::::::

There should be 3 tools presented.

Note that when I configure VSCode with the MCP server, the JSONRPC seems to be working fine for the initialize and tools/list commands. VSCode shows the server and the tools list. However, I sometimes see the resource content show up in VS Code, but I think it is used when I perform prompts.

[jayhamilton]

update ... just started the MCP server in VSCode today, after an update to the VSCODE MCP server extension. When starting my MCP server in VSCode, the VSCode logs show the following:

2025-08-06 11:19:19.741 [info] Starting server from LocalProcess extension host
2025-08-06 11:19:19.743 [info] Connection state: Starting
2025-08-06 11:19:19.743 [info] Connection state: Running
2025-08-06 11:19:22.690 [warning] Failed to parse message: "::::::::::{\"jsonrpc\":\"2.0\",\"id\":1,\"result\":{\"protocolVersion\":\"2024-11-05\",\"capabilities\":{\"completions\":{},\"logging\":{},\"prompts\":{\"listChanged\":true},\"resources\":{\"subscribe\":false,\"listChanged\":true},\"tools\":{\"listChanged\":true}},\"serverInfo\":{\"name\":\"sds-mcp-server\",\"version\":\"1.0.0\"}}}\n"
2025-08-06 11:19:24.705 [info] Waiting for server to respond to `initialize` request...
2025-08-06 11:19:29.706 [info] Waiting for server to respond to `initialize` request...
2025-08-06 11:19:34.695 [info] Waiting for server to respond to `initialize` request...
2025-08-06 11:19:39.697 [info] Waiting for server to respond to `initialize` request...
2025-08-06 11:19:44.697 [info] Waiting for server to respond to `initialize` request...