MCP Server with STDIO protocol fails to load @MCPTool annotated methods

[ilayaperumalg]

From @sivaprasadreddy:

I have created a simple MCP Server with STDIO protocol. Its working fine with @tool and registering a List bean. But when I use @mcptool and test it from MCPInspector, it is throwing the following error:

STDIO transport: command=/Users/siva/.local/share/mise/installs/java/temurin-24.0.1+9/bin/java, args=-jar,/Users/siva/Siva/Projects/My/sivalabs-mcp/sivalabs-mcp-server-stdio/target/sivalabs-mcp-server-stdio-0.0.1.jar
Created client transport
Created server transport
Received POST message for sessionId 080fda54-4f11-4279-8d52-ae23fc5e4937
Error from MCP server: SyntaxError: Expected property name or '}' in JSON at position 1 (line 1 column 2)
    at JSON.parse (<anonymous>)
    at deserializeMessage (file:///Users/siva/.npm/_npx/9eac9498388ae25e/node_modules/@modelcontextprotocol/sdk/dist/esm/shared/stdio.js:26:44)
    at ReadBuffer.readMessage (file:///Users/siva/.npm/_npx/9eac9498388ae25e/node_modules/@modelcontextprotocol/sdk/dist/esm/shared/stdio.js:19:16)
    at StdioClientTransport.processReadBuffer (file:///Users/siva/.npm/_npx/9eac9498388ae25e/node_modules/@modelcontextprotocol/sdk/dist/esm/client/stdio.js:141:50)
    at Socket.<anonymous> (file:///Users/siva/.npm/_npx/9eac9498388ae25e/node_modules/@modelcontextprotocol/sdk/dist/esm/client/stdio.js:103:22)
    at Socket.emit (node:events:518:28)
    at addChunk (node:internal/streams/readable:561:12)
    at readableAddChunkPushByteMode (node:internal/streams/readable:512:3)
    at Readable.push (node:internal/streams/readable:392:5)
    at Pipe.onStreamRead (node:internal/stream_base_commons:189:23)

I tried the weather sample from spring-ai-examples and it is also throwing the same error.

Here is a reproducer example: https://github.com/sivaprasadreddy/sivalabs-mcp/tree/ai-1.1.0-SNAPSHOT

Checkout the branch ai-1.1.0-SNAPSHOT
cd sivalabs-mcp-server-stdio
mvn clean package
npx @modelcontextprotocol/inspector@latest
Transport Type: STDIO
Command: java
Arguments: -jar /sivalabs-mcp/sivalabs-mcp-server-stdio/target/sivalabs-mcp-server-stdio-0.0.1.jar

NOTE: https://github.com/mcptool support working fine with webmvc support (sse, streamable, stateless).