Copilot can't use the streamable transport

[topikachu]

Jenkins and plugins versions report

Environment

vs code copilot 1.350.0

What Operating System are you using (both controller, and any agents involved in the problem)?

mac of mcp client

Reproduction steps

{
	"servers": {
		"jenkins": {
			"type": "http",
			"url": "http://localhost:8080/mcp-server/mcp",
			"tools": [
				"*"
			],
			"headers": {
				"Authorization": "Basic <user:token in base64>"
			}
		}
	},
	"inputs": []
}

Expected Results

mcp works

Actual Results

The agent hangs when calling the MCP tool with such an error

[warning] Unexpected 200 response for request: id: b7226ee9-36a3-49a8-becf-7aa85e187bef

Anything else?

No response

Are you interested in contributing a fix?

No response

[olamy]

Could it be some protocol version issue? (modelcontextprotocol/java-sdk#444)
I can see some logs in Jenkins

2025-08-05 22:15:34.609+0000 [id=266]	WARNING	i.m.server.McpAsyncServer#lambda$asyncInitializeRequestHandler$5: Client requested unsupported protocol version: 2025-03-26, so the server will suggest the 2024-11-05 version instead

Maybe you can have some tests with a snapshot of the java-sdk?

[topikachu]

I tested the new plugin that supports the Streamable protocol.
Jenkins shows the log as
2025-08-06 00:41:36.048+0000 [id=22] WARNING i.m.server.McpAsyncServer#lambda$asyncInitializeRequestHandler$5: Client requested unsupported protocol version: 2025-06-18, so the server will suggest the 2025-03-26 version instead

As I debug, Copilot initializes one POST method and one SSE GET method.
And Copilot shows

 Unexpected 200 response for request: id: b7226ee9-36a3-49a8-becf-7aa85e187bef

Copilot can trigger a MCP tool call, and the server returns the message correctly. But Copilot shows similar Unexpected 200 response for request and hangs.

I'm still investigating this issue.

[topikachu]

The issue is disappared after upgraded both the Jenkins MCP server plugin and Copilot.
Close the issue.