Invalid JSON RPC requests do not respond with an error

[joshcanhelp]

I noticed that this request:

{"jsonrpc": "2.0", "id": 1, "method": "tools/lit", "params": {}}

... returns an error response (code -32601) as expected but this:

{"jsonrpc": "2.0", "id": 1, "method_": "tools/list", "params": {}}

... returns nothing. I would expect that a missing method property or an unknown root property like methodX would throw and error. The JSON-RPC 2.0 spec says the server should return:

• -32600 "Invalid Request" for malformed JSON-RPC (missing required fields like method)
• -32602 "Invalid params" for bad parameters

I think the SDK should handle these but I'm not even able to write validation logic in my application code because an invalid RPC request never reaches my handler.

Claude tells me I can do something like this:

class ValidatingStdioTransport extends StdioServerTransport {
  // Override message handling to add validation
}

.. but I don't love that.

If a maintainer agrees that this validation should be in the SDK, I'd be more than happy to write a PR! Thank you for all your work on this!

[JBB0807]

I tried it on my end, and here’s what I found: in the event of a schema validation error, the SDK currently returns "Parse Error" -32700, along with a hard-to-read message in the data field.

{"jsonrpc":"2.0","error":{"code":-32700,"message":"Parse error","data":"[\n {\n \"code\": \"invalid_union\",\n \"unionErrors\": [\n {\n \"issues\": [\n {\n \"code\": \"invalid_type\",\n \"expected\": \"string\",\n \"received\": \"undefined\",\n \"path\": [\n \"method\"\n ],\n \"message\": \"Required\"\n },\n {\n \"code\":......

Can I work on this item and improve the error handling?