Multiple STDIO servers cause Regex error

[Lizzergas]

Having two MCP servers with STDIO transport layer causes Claude Client to fail with this error:
tools.0.FrontendRemoteMcpToolDefinition.name: String should match pattern '^[a-zA-Z0-9_]{1,64}$'

When enabling STDIO MCP servers individually, there is no error.

Here is my config that I am using.

    "todo-mcp": {
      "command": "java",
      "args": [
        "-jar",
        "/Users/lizz/src/kotlin/kotlin-playground/todo-mcp/todo-mcp-server/build/libs/todo-mcp-server-1.0-SNAPSHOT-all.jar"
      ]
    },
    "gcal-mcp": {
      "command": "java",
      "args": [
        "-jar",
        "/Users/lizz/src/kotlin/kotlin-playground/lizz-gcal-mcp/build/libs/lizz-gcal-mcp-1.0-SNAPSHOT-all.jar"
      ]
    },

To Reproduce

Steps to reproduce the behavior:

1. Create two simple local MCP servers with at least one tool that can print anything like "Hello World
   1.1. Or git clone my simple MCP servers and use them for reproduction. Repo 1 / Repo 2
2. Connect and enable both of them in any MCP host
3. Test out by writing these prompts: "list out my todos" or "run gcal Test Tool"

Expected behavior
Running multiple local MCP servers should work with any client

Additional context

• Note: I haven't tested with other MCP hosts and clients
• No error logs are found in Claude logs in any given tools

[Lizzergas]

This might be related to these issues:

modelcontextprotocol/modelcontextprotocol#986
modelcontextprotocol/go-sdk#169