Bug: MCP auth fails because of unrecognised elicitation.form field

[fourslashw]

Graylog mcp does not work in latest versions of cloud code because graylog does not recognise params.capabilities.elicitation.form field, which is part of the MCP standart: https://modelcontextprotocol.io/specification/2025-11-25/client/elicitation

Possible Solution

Allow unknown fields in Elicitation class or define it to MCP specs

Current workaround

Use Claude 2.1.6 where elicitation is disabled

Steps to Reproduce (for bugs)

Fails with elicitation.from:

  curl -s -X POST https://MYGRAYLOGSERVER/api/mcp \
    -H "Content-Type: application/json" \
    -H "Accept: application/json, text/event-stream" \
    -H "Authorization: Basic MYTOKENHERE" \
    -d '{
      "jsonrpc": "2.0",
      "id": 0,
      "method": "initialize",
      "params": {
        "protocolVersion": "2024-11-05",
        "capabilities": {
          "elicitation": {
            "form": {}
          },
          "roots": { "listChanged": true },
          "sampling": {}
        },
        "clientInfo": {
          "name": "claude-code",
          "version": "2.1.74"
        }
      }
    }'


{"jsonrpc":"2.0","id":0,"error":{"code":-32603,"message":"Unrecognized field \"form\" (class io.modelcontextprotocol.spec.McpSchema$ClientCapabilities$Elicitation), not marked as ignorable (0 known properties: ])\n at [Source: UNKNOWN; byte offset: #UNKNOWN] (through reference chain: io.modelcontextprotocol.spec.McpSchema$InitializeRequest[\"capabilities\"]->io.modelcontextprotocol.spec.McpSchema$ClientCapabilities[\"elicitation\"]->io.modelcontextprotocol.spec.McpSchema$ClientCapabilities$Elicitation[\"form\"])"}}

Works without:

curl -s -X POST https://MYGRAYLOGSERVER/api/mcp \
     -H "Content-Type: application/json" \
     -H "Accept: application/json, text/event-stream" \
     -H "Authorization: Basic MYTOKENHERE" \
     -d '{
       "jsonrpc": "2.0",
       "id": 0,
       "method": "initialize",
       "params": {
         "protocolVersion": "2024-11-05",
         "capabilities": {
           "elicitation": {
           },
           "roots": { "listChanged": true },
           "sampling": {}
         },
         "clientInfo": {
           "name": "claude-code",
           "version": "2.1.74"
         }
       }
     }'

{"jsonrpc":"2.0","id":0,"result":{"protocolVersion":"2025-06-18","capabilities":{"prompts":{"listChanged":false},"resources":{"subscribe":false,"listChanged":false},"tools":{"listChanged":false}},"serverInfo":{"name":"Graylog","version":"7.0.5+1a1d8ce"}}}

Your Environment

• Graylog Version: 7.0.5+1a1d8ce
• Java Version: openjdk 21.0.10 2026-01-20
• OpenSearch Version: -
• MongoDB Version: -
• Operating System: -
• Browser version: -

[bobazooba]

That really hurts!

[vladdekhanov]

Same here! Any other reliable workarounds someone found? Claude 2.1.6 helped me to establish connection, but agent still can't do request to read graylog messages

[dylanrichards]

I had the same issue.
This seems to have been fixed after updating Graylog to 7.1.0-alpha.2

Java MCP SDK issue:
modelcontextprotocol/java-sdk#724
Fix PR:
modelcontextprotocol/java-sdk#731
Fixed version v0.17.1
modelcontextprotocol/java-sdk@a2a81cd

Graylog Bump io.modelcontextprotocol.sdk:mcp-bom from 0.17.0 to 0.17.1
164795d

[monrax]

Fixed in #25748
This will be included in next (7.0.7) release. Thank you!