MCP tool calls execute as anonymous despite valid Basic authentication

[vineett]

Jenkins and plugins versions report

Jenkins: 2.568.1
OS: Linux - 5.4.17-2136.356.4.2.el7uek.x86_64
Java: 21.0.2 - Oracle Corporation (Java HotSpot(TM) 64-Bit Server VM)

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

Controller OS: Oracle Enterprise Linux
Client: Codex desktop on Windows.
No Jenkins agents are involved in this MCP request.

Reproduction steps

1. Configure an MCP client to use the Streamable HTTP endpoint /mcp-server/mcp with Authorization: Basic <base64(username:api-token)>.
2. Verify the same header directly against <jenkins-url>/whoAmI/api/json; it returns HTTP 200 with anonymous: false.
3. Connect the MCP client and call the built-in whoAmI tool.
4. Observe the MCP error: AccessDeniedException3: anonymous is missing the Overall/Read permission.
5. With FINE logging enabled, observe that the tool call reaches io.jenkins.plugins.mcp.server.tool.McpToolWrapper.call, then fails at ACL.checkPermission from a Reactor SchedulerTask worker thread.

Expected Results

The MCP whoAmI tool should execute with the authenticated Jenkins principal from the Basic-authenticated request and return that principal.

Actual Results

The tool call is executed as anonymous and fails because anonymous lacks Overall/Read. The direct Jenkins REST whoAmI API call using the same Basic header authenticates successfully.

Anything else?

No response

Are you interested in contributing a fix?

I can help validate a proposed fix, but I am not currently planning to contribute code.

[MarkRx]

Could you paste your mcp.json configuration along with which tool you are using? I've found that VSCode, GH Copilot, and Claude code use have different nuances when it comes to setting up the mcp.json config.